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Intercept theorem

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Suppose S is the common starting point of two rays, and two parallel lines are intersecting those two rays (see figure). Let A, B be the intersections of the first ray with the two parallels, such that B is further away from S than A, and similarly C, D are the intersections of the second ray with
1260:, i.e. it can be used to prove the properties of similar triangles and similar triangles can be used to prove the intercept theorem. By matching identical angles you can always place two similar triangles in one another so that you get the configuration in which the intercept theorem applies; and 5301:.. without trouble or the assistance of any instrument merely set up a stick at the extremity of the shadow cast by the pyramid and, having thus made two triangles by the intercept of the sun's rays, ... showed that the pyramid has to the stick the same ratio which the shadow has to the shadow 1463: 1728:
It took more than 2000 years until all three of them were finally shown to be impossible. This was achieved in the 19th century with the help of algebraic methods, that had become available by then. In order to reformulate the three problems in algebraic terms using
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give a description that strictly speaking does not require the intercept theorem, but can rely on a simple observation only, namely that at a certain point of the day the length of an object's shadow will match its height. Laertius quotes a statement of the philosopher
2282: 1741:). In particular it is important to assure that for two given line segments, a new line segment can be constructed, such that its length equals the product of lengths of the other two. Similarly one needs to be able to construct, for a line segment of length 2292:
The intercept theorem can be used to determine a distance that cannot be measured directly, such as the width of a river or a lake, the height of tall buildings or similar. The graphic to the right illustrates measuring the width of a river. The segments
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Thales measured the length of the pyramid's base and the height of his pole. Then at the same time of the day he measured the length of the pyramid's shadow and the length of the pole's shadow. This yielded the following data:
904:, then each parallel contains more than one line segment and the ratio of two line segments on one parallel equals the ratio of the according line segments on the other parallel. For instance if there's a third ray starting at 592: 2174: 3448: 3284: 1678:{\displaystyle {\frac {\|\lambda \cdot {\vec {a}}\|}{\|{\vec {a}}\|}}={\frac {\|\lambda \cdot {\vec {b}}\|}{\|{\vec {b}}\|}}={\frac {\|\lambda \cdot ({\vec {a}}+{\vec {b}})\|}{\|{\vec {a}}+{\vec {b}}\|}}=|\lambda |} 1458: 3118: 1230:
For the second equation the converse is true as well, that is if the 3 rays are intercepted by two lines and the ratios of the according line segments on each line are equal, then those 2 lines must be parallel.
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An elementary proof of the theorem uses triangles of equal area to derive the basic statements about the ratios (claim 1). The other claims then follow by applying the first claim and contradiction.
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Hieronymus says that measured the height of the pyramids by the shadow they cast, taking the observation at the hour when our shadow is of the same length as ourselves (i.e. as our own height).
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Thales discovered how to obtain the height of pyramids and all other similar objects, namely, by measuring the shadow of the object at the time when a body and its shadow are equal in length.
2825: 2761: 4709: 2482: 2185: 2081:. The following description illustrates the use of the intercept theorem to compute the height of the pyramid. It does not, however, recount Thales' original work, which was lost. 4616: 2011: 1979: 1917: 1859: 2639: 1287: 2697: 2668: 2956: 2832: 4526: 5274:
No original work of Thales has survived. All historical sources that attribute the intercept theorem or related knowledge to him were written centuries after his death.
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If the midpoints of the two non-parallel sides of a trapezoid are connected, then the resulting line segment is parallel to the other two sides of the trapezoid.
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yields V figure with identical measures for which the original theorem now applies. The third statement (converse) however does not remain true for lines.
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holds then the two intercepting lines are parallel. However, the converse of the second statement is not true (see graphic for a counterexample).
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This article is about the theorem about the ratios of various line segments. For the special case of the inscribed angle theorem, see
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If the midpoints of two triangle sides are connected then the resulting line segment is parallel to the third triangle side (
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The converse of the first statement is true as well, i.e. if the two rays are intercepted by two arbitrary lines and
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the two parallels such that D is further away from S than C. In this configuration the following statements hold:
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The ratio of the two segments on the same ray starting at S equals the ratio of the segments on the parallels:
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The ratio of any two segments on the first ray equals the ratio of the according segments on the second ray:
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gives an account that may suggest Thales knowing the intercept theorem or at least a special case of it:"
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The intercept theorem can be used to prove that a certain construction yields parallel line (segment)s.
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are of equal length. As those triangles share the same baseline, their areas are identical. So we have
1791:. The intercept theorem can be used to show that for both cases, that such a construction is possible. 1375:{\displaystyle \lambda \cdot ({\vec {a}}+{\vec {b}})=\lambda \cdot {\vec {a}}+\lambda \cdot {\vec {b}}} 5973: 5110: 1984: 1952: 1890: 1832: 6717: 6688: 6048: 5903: 3070:{\displaystyle {\frac {|\triangle SCA|}{|\triangle SDA|}}={\frac {|\triangle SCA|}{|\triangle SCB|}}} 2946:{\displaystyle {\frac {|\triangle SCA|}{|\triangle CDA|}}={\frac {|\triangle SCA|}{|\triangle CBA|}}} 2612: 6851: 6585: 6128: 2673: 2644: 1945:
equidistant points, then draw the line through the last point and B and parallel line through the
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There are three famous problems in elementary geometry which were posed by the Greeks in terms of
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The first two statements remain true if the two rays get replaced by two lines intersecting in
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On ratios of line segments formed when 2 intersecting lines are cut by a pair of parallels
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in the desired ratio. The graphic to the right shows the partition of a line segment
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is not located between the two parallels, the original theorem applies directly. If
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Mit harmonischen Verhältnissen zu Kegelschnitten: Perlen der klassischen Geometrie.
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Mit harmonischen Verhältnissen zu Kegelschnitten: Perlen der klassischen Geometrie.
4934:. This is a contradiction, so the assumption could not have been true, which means 1261: 761:, either it lies between the 2 parallels (X figure) or it does not (V figure). If 6413: 6403: 6297: 6023: 5279: 1730: 6673: 6668: 6496: 6388: 6368: 6196: 5753: 5723: 1244: 55: 4376: 1814: 1688: 587:{\displaystyle {\frac {|SA|}{|SB|}}={\frac {|SC|}{|SD|}}={\frac {|AC|}{|BD|}}} 6911: 6633: 6501: 6471: 6292: 6100: 6043: 5465: 5066: 2179:
Knowing A, B and C he was now able to apply the intercept theorem to compute
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Arranging two similar triangles, so that the intercept theorem can be applied
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Ancient Mathematics. History of Mathematics in Ancient Greece and Hellenism
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the intercept theorem configuration always contains two similar triangles.
51: 5593: 2169:{\displaystyle C=65~{\text{m}}+{\frac {230~{\text{m}}}{2}}=180~{\text{m}}} 6189: 6077: 5783: 5768: 5432: 3443:{\displaystyle {\frac {|SC||AF|}{|SD||AF|}}={\frac {|SA||EC|}{|SB||EC|}}} 3279:{\displaystyle {\frac {|SC||AF|}{|CD||AF|}}={\frac {|SA||EC|}{|AB||EC|}}} 6175: 6094: 6033: 6028: 5968: 5953: 5898: 5883: 5838: 5778: 5763: 5743: 5713: 5678: 5599: 5417: 1453:{\displaystyle \|\lambda {\vec {a}}\|=|\lambda |\cdot \ \|{\vec {a}}\|} 5622: 3113:{\displaystyle {\tfrac {{\text{baseline}}\cdot {\text{altitude}}}{2}}} 99: 5928: 5913: 5863: 5758: 5748: 5733: 5703: 2523: 2511: 713: 705: 78: 74: 6065: 5843: 5688: 5296: 2539:
The theorem is traditionally attributed to the Greek mathematician
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applied the intercept theorem to determine the height of the
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According to some historical sources the Greek mathematician
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Lothar Redlin, Ngo Viet, Saleem Watson: "Thales' Shadow",
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with a common starting point are intercepted by a pair of
4333:{\displaystyle {\frac {|SA|}{|SB|}}={\frac {|AC|}{|BD|}}} 4233:{\displaystyle {\frac {|SA|}{|SB|}}={\frac {|DG|}{|BD|}}} 1267: 1220:{\displaystyle {\frac {|AE|}{|EC|}}={\frac {|BF|}{|FD|}}} 1120:{\displaystyle {\frac {|AE|}{|BF|}}={\frac {|EC|}{|FD|}}} 689:{\displaystyle {\frac {|SA|}{|AB|}}={\frac {|SC|}{|CD|}}} 441:{\displaystyle {\frac {|SA|}{|SB|}}={\frac {|SC|}{|SD|}}} 341:{\displaystyle {\frac {|SB|}{|AB|}}={\frac {|SD|}{|CD|}}} 241:{\displaystyle {\frac {|SA|}{|AB|}}={\frac {|SC|}{|CD|}}} 1700:
Algebraic formulation of compass and ruler constructions
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Lorenz Halbeisen, Norbert Hungerbühler, Juan Läuchli:
3087: 741:. In this case there are two scenarios with regard to 4986: 4963: 4940: 4907: 4887: 4867: 4840: 4820: 4719: 4625: 4534: 4501: 4478: 4458: 4435: 4412: 4389: 4347: 4246: 4146: 4094: 4071: 4048: 4005: 3905: 3731: 3698: 3665: 3562: 3461: 3292: 3128: 3085: 2959: 2835: 2769: 2705: 2676: 2647: 2615: 2603:) denote its area and for a line segment its length. 2579: 2398: 2392:
are measured and used to compute the wanted distance
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lies between the two parallels, then a reflection of
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intercept theorem with a pair of intersecting lines
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UTB Schöningh. pp. 124–126. 5657: 5643: 4704:{\displaystyle |SB|={\frac {|SD||SA|}{|SC|}}} 2477:{\displaystyle |AB|={\frac {|AC||FE|}{|FC|}}} 700: 94: 5416:, Vol. 73, No. 5 (Dec., 2000), pp. 347-353 ( 4429:are not parallel. Then the parallel line to 3079:Plugging in the formula for triangle areas ( 1653: 1623: 1618: 1576: 1564: 1549: 1544: 1523: 1511: 1496: 1491: 1470: 1447: 1432: 1407: 1389: 1252:The intercept theorem is closely related to 864:If there are more than two rays starting at 81:, although its first known proof appears in 5105: 5103: 5101: 4712:and on the other hand from claim 1 we have 5650: 5636: 5338:Milestones in Analog and Digital Computing 5178: 2493:Parallel lines in triangles and trapezoids 717:intercept theorem with more than two lines 5497: 5316:Moralia, The Dinner of the Seven Wise Men 4006: 3906: 3563: 3462: 3452:Canceling the common factors results in: 1887:ratio, draw an arbitrary angle in A with 5351: 5330: 5224: 5135: 5098: 5017: 5015: 3899:Using (b) again this simplifies to: (c) 2064: 2056: 1825:Dividing a line segment in a given ratio 1243: 712: 704: 106: 98: 5372: 5268: 5059: 5045: 5043: 2047: 1919:as one leg. On the other leg construct 1024:, then the following equalities holds: 884:or more than two lines intersecting at 6910: 6679:Latin translations of the 12th century 5431: 5406: 5021: 1706:compass and straightedge constructions 1268:Scalar multiplication in vector spaces 6409:Straightedge and compass construction 5631: 5385: 5012: 2534: 1949:th point. This parallel line divides 1256:. It is equivalent to the concept of 6374:Incircle and excircles of a triangle 5395:. Cambridge University Press, 2015, 5205: 5040: 4065:through A. This parallel intersects 1829:To divide an arbitrary line segment 66:. It is traditionally attributed to 5210:(in German). Vieweg. pp. 5–7. 5199: 4611:{\displaystyle |SB|:|SA|=|SD|:|SC|} 1234: 13: 4375: 4034: 3047: 3023: 2992: 2968: 2923: 2899: 2868: 2844: 2800: 2775: 2736: 2711: 2677: 2648: 2573:For a triangle the vertical bars ( 2562: 2522: 2510: 924:and intersecting the parallels in 14: 6934: 5587: 5380:An Axiomatic Approach to Geometry 5128: 2095:length of the pyramid base: 230 m 6891: 6878: 5287:(3rd century BC) about Thales: " 2485: 2040: 2006:{\displaystyle {\overline {AB}}} 1974:{\displaystyle {\overline {AB}}} 1912:{\displaystyle {\overline {AB}}} 1854:{\displaystyle {\overline {AB}}} 1813: 1801: 1687: 1240:Similarity and similar triangles 4042:Draw an additional parallel to 1761:, a new line segment of length 1694: 6711:A History of Greek Mathematics 6224:The Quadrature of the Parabola 5472:. AMS. pp. 10–13, 16–18. 5439:. BLoomsbury. pp. 84–87. 5437:Teaching and Learning Geometry 5172: 5073:. AMS. pp. 10–13, 16–18. 4881:and have the same distance to 4795: 4784: 4777: 4766: 4761: 4750: 4739: 4721: 4694: 4683: 4676: 4665: 4660: 4649: 4638: 4627: 4604: 4593: 4585: 4574: 4566: 4555: 4547: 4536: 4323: 4312: 4305: 4294: 4280: 4269: 4262: 4251: 4223: 4212: 4205: 4194: 4180: 4169: 4162: 4151: 4126: 4115: 4107: 4096: 3983: 3972: 3965: 3954: 3940: 3929: 3922: 3911: 3880: 3869: 3861: 3850: 3843: 3832: 3827: 3816: 3801: 3790: 3782: 3771: 3764: 3753: 3748: 3737: 3711: 3700: 3678: 3667: 3640: 3629: 3622: 3611: 3597: 3586: 3579: 3568: 3539: 3528: 3521: 3510: 3496: 3485: 3478: 3467: 3433: 3422: 3417: 3406: 3399: 3388: 3383: 3372: 3358: 3347: 3342: 3331: 3324: 3313: 3308: 3297: 3269: 3258: 3253: 3242: 3235: 3224: 3219: 3208: 3194: 3183: 3178: 3167: 3160: 3149: 3144: 3133: 3060: 3043: 3036: 3019: 3005: 2988: 2981: 2964: 2936: 2919: 2912: 2895: 2881: 2864: 2857: 2840: 2813: 2796: 2788: 2771: 2749: 2732: 2724: 2707: 2634:{\displaystyle CA\parallel BD} 2589: 2581: 2467: 2456: 2449: 2438: 2433: 2422: 2411: 2400: 2378: 2367: 2345: 2334: 2312: 2301: 2288:Measuring the width of a river 2089:height of the pole (A): 1.63 m 1671: 1663: 1647: 1632: 1615: 1609: 1594: 1585: 1558: 1538: 1505: 1485: 1441: 1422: 1414: 1401: 1366: 1345: 1327: 1321: 1306: 1297: 1210: 1199: 1192: 1181: 1167: 1156: 1149: 1138: 1110: 1099: 1092: 1081: 1067: 1056: 1049: 1038: 679: 668: 661: 650: 636: 625: 618: 607: 577: 566: 559: 548: 534: 523: 516: 505: 491: 480: 473: 462: 431: 420: 413: 402: 388: 377: 370: 359: 331: 320: 313: 302: 288: 277: 270: 259: 231: 220: 213: 202: 188: 177: 170: 159: 73:. It was known to the ancient 1: 5623:intercept theorem interactive 5425: 5323:Lives of Eminent Philosophers 2692:{\displaystyle \triangle CBA} 2663:{\displaystyle \triangle CDA} 2506:Midpoint theorem of triangles 36:basic proportionality theorem 6492:Intersecting secants theorem 5501:The Four Pillars of Geometry 5468:; Friedrich, Thomas (2008). 5325:, Chapter 1. Thales, para.27 5069:; Friedrich, Thomas (2008). 2053:Height of the Cheops pyramid 1998: 1966: 1904: 1846: 50:about the ratios of various 7: 6487:Intersecting chords theorem 6354:Doctrine of proportionality 5583:, pp. 191–208 (German) 5393:Computation, Proof, Machine 5382:. Springer, 2013, pp. 10–13 5159:does not necessarily imply 5153:| / | 5145:| / | 5125:, pp. 191–208 (German) 4521:{\displaystyle B_{0}\neq B} 2098:shadow of the pyramid: 65 m 2092:shadow of the pole (B): 2 m 130:does not necessarily imply 124:| / | 116:| / | 103:intercept theorem with rays 10: 6939: 6923:Theorems in plane geometry 6183:On the Sphere and Cylinder 6136:On the Sizes and Distances 5054:SchĂĽlerduden: Mathematik I 4374: 4367: 4033: 4026: 4013:{\displaystyle \,\square } 2561: 2554: 2518: 2502: 1811:Construction of an inverse 1808: 1796: 701:Extensions and conclusions 95:Formulation of the theorem 18: 6885:Ancient Greece portal 6874: 6824: 6702: 6689:Philosophy of mathematics 6659: 6652: 6626: 6604:Ptolemy's table of chords 6548: 6530: 6429: 6422: 6278: 6240: 6057: 5665: 5659:Ancient Greek mathematics 4133:{\displaystyle |AC|=|DG|} 2596:{\displaystyle |\ldots |} 1799:Construction of a product 6556:Aristarchus's inequality 6129:On Conoids and Spheroids 5498:Stillwell, John (2005). 5006: 4993:{\displaystyle \square } 4861:are on the same side of 4354:{\displaystyle \square } 2546: 54:that are created if two 6664:Ancient Greek astronomy 6477:Inscribed angle theorem 6467:Greek geometric algebra 6122:Measurement of a Circle 5538:Geometry by Its History 5235:Geometry by Its History 5180:Kazarinoff, Nicholas D. 4927:{\displaystyle B=B_{0}} 3659:Now use (b) to replace 3120:) transforms that into 6898:Mathematics portal 6684:Non-Euclidean geometry 6639:Mouseion of Alexandria 6512:Tangent-secant theorem 6462:Geometric mean theorem 6447:Exterior angle theorem 6442:Angle bisector theorem 6146:On Sizes and Distances 5168: 4994: 4974: 4951: 4928: 4895: 4875: 4855: 4828: 4806: 4705: 4612: 4522: 4489: 4466: 4446: 4423: 4400: 4380: 4355: 4334: 4234: 4134: 4082: 4059: 4039: 4014: 3994: 3891: 3719: 3686: 3651: 3550: 3444: 3280: 3114: 3071: 2947: 2821: 2757: 2693: 2664: 2635: 2597: 2567: 2527: 2515: 2478: 2386: 2353: 2320: 2278: 2170: 2102:From this he computed 2070: 2062: 2033: 2007: 1975: 1939: 1913: 1881: 1855: 1785: 1784:{\displaystyle a^{-1}} 1755: 1679: 1454: 1376: 1249: 1221: 1121: 1018: 998: 984:is further away from 978: 958: 938: 918: 898: 878: 855: 835: 815: 795: 775: 755: 735: 718: 710: 690: 588: 442: 342: 242: 139: 104: 6586:Pappus's area theorem 6522:Theorem of the gnomon 6399:Quadratrix of Hippias 6322:Circles of Apollonius 6270:Problem of Apollonius 6248:Constructible numbers 6072:Archimedes Palimpsest 5604:Alexander Bogomolny: 5542:. Springer. pp.  5239:. Springer. pp.  5139: 4995: 4975: 4952: 4929: 4896: 4876: 4856: 4854:{\displaystyle B_{0}} 4829: 4807: 4706: 4613: 4523: 4490: 4467: 4447: 4424: 4401: 4379: 4356: 4335: 4235: 4135: 4083: 4060: 4038: 4015: 3995: 3892: 3720: 3687: 3652: 3551: 3445: 3281: 3115: 3072: 2948: 2827:as well. This yields 2822: 2758: 2694: 2665: 2636: 2598: 2566: 2526: 2514: 2479: 2387: 2354: 2321: 2279: 2171: 2068: 2060: 2034: 2008: 1976: 1940: 1914: 1882: 1856: 1786: 1756: 1733:, one needs to match 1680: 1455: 1377: 1282:scalar multiplication 1247: 1222: 1122: 1019: 999: 979: 959: 939: 919: 899: 879: 856: 836: 816: 796: 776: 756: 736: 716: 708: 691: 589: 443: 343: 243: 110: 102: 40:side splitter theorem 6802:prehistoric counting 6599:Ptolemy's inequality 6540:Apollonius's theorem 6379:Method of exhaustion 6349:Diophantine equation 6339:Circumscribed circle 6156:On the Moving Sphere 5504:. Springer. p.  5414:Mathematics Magazine 5206:Kunz, Ernst (1991). 5186:, Dover, p. 3, 5111:Norbert HungerbĂĽhler 4984: 4980:are indeed parallel 4961: 4938: 4905: 4885: 4865: 4838: 4818: 4717: 4623: 4532: 4499: 4476: 4456: 4433: 4410: 4387: 4345: 4244: 4144: 4092: 4069: 4046: 4003: 3903: 3729: 3718:{\displaystyle |SC|} 3696: 3685:{\displaystyle |SA|} 3663: 3560: 3459: 3290: 3126: 3083: 2957: 2833: 2767: 2703: 2674: 2645: 2613: 2577: 2396: 2385:{\displaystyle |FE|} 2363: 2352:{\displaystyle |CA|} 2330: 2319:{\displaystyle |CF|} 2297: 2186: 2109: 2048:Measuring and survey 2017: 1985: 1953: 1923: 1891: 1865: 1833: 1765: 1745: 1739:constructible number 1713:Trisecting the angle 1464: 1386: 1288: 1131: 1031: 1008: 988: 968: 948: 928: 908: 888: 868: 845: 825: 805: 785: 765: 745: 725: 600: 455: 352: 252: 152: 6888: • 6694:Neusis construction 6614:Spiral of Theodorus 6507:Pythagorean theorem 6452:Euclidean algorithm 6394:Lune of Hippocrates 6263:Squaring the circle 6019:Theon of Alexandria 5694:Aristaeus the Elder 5470:Elementary Geometry 5184:Ruler and the Round 5071:Elementary Geometry 5022:Schupp, H. (1977). 4140:and due to claim 1 4088:in G. Then one has 2641:, the altitudes of 2032:{\displaystyle 5:3} 1938:{\displaystyle m+n} 1880:{\displaystyle m:n} 1723:Squaring the circle 68:Greek mathematician 48:elementary geometry 6918:Euclidean geometry 6581:Menelaus's theorem 6571:Irrational numbers 6384:Parallel postulate 6359:Euclidean geometry 6327:Apollonian circles 5869:Isidore of Miletus 5610:and in particular 5357:Dietmar Herrmann: 5340:. Springer, 2021, 5336:Herbert Bruderer: 5291:". Pliny writes: " 5169: 5109:Lorenz Halbeisen, 5024:Elementargeometrie 4990: 4973:{\displaystyle BD} 4970: 4950:{\displaystyle AC} 4947: 4924: 4891: 4871: 4851: 4824: 4802: 4701: 4608: 4518: 4488:{\displaystyle SA} 4485: 4462: 4445:{\displaystyle AC} 4442: 4422:{\displaystyle BD} 4419: 4399:{\displaystyle AC} 4396: 4381: 4351: 4330: 4230: 4130: 4081:{\displaystyle BD} 4078: 4058:{\displaystyle SD} 4055: 4040: 4010: 3990: 3887: 3715: 3682: 3647: 3546: 3440: 3276: 3110: 3108: 3067: 2943: 2817: 2753: 2689: 2660: 2631: 2593: 2568: 2535:Historical aspects 2528: 2516: 2474: 2382: 2349: 2316: 2274: 2166: 2071: 2063: 2029: 2003: 1971: 1935: 1909: 1877: 1851: 1781: 1751: 1675: 1450: 1372: 1250: 1217: 1117: 1014: 994: 974: 954: 934: 914: 894: 874: 851: 831: 811: 791: 771: 751: 731: 719: 711: 686: 584: 438: 338: 238: 140: 105: 42:, is an important 6905: 6904: 6870: 6869: 6622: 6621: 6609:Ptolemy's theorem 6482:Intercept theorem 6332:Apollonian gasket 6258:Doubling the cube 6231:The Sand Reckoner 5595:Intercept Theorem 5553:978-3-642-29163-0 5515:978-0-387-25530-9 5378:Francis Borceux: 5367:978-3-662-66493-3 5361:, Springer 2022, 5276:Diogenes Laertius 5250:978-3-642-29163-0 5004: 5003: 4894:{\displaystyle S} 4874:{\displaystyle S} 4827:{\displaystyle B} 4800: 4699: 4618:is true, we have 4465:{\displaystyle D} 4365: 4364: 4328: 4285: 4228: 4185: 4024: 4023: 3988: 3945: 3885: 3866: 3806: 3787: 3645: 3602: 3544: 3501: 3438: 3363: 3274: 3199: 3107: 3101: 3093: 3065: 3010: 2941: 2886: 2541:Thales of Miletus 2532: 2531: 2472: 2272: 2268: 2258: 2255: 2251: 2242: 2238: 2228: 2224: 2211: 2164: 2160: 2150: 2144: 2140: 2127: 2123: 2069:computing C and D 2001: 1969: 1907: 1849: 1822: 1821: 1754:{\displaystyle a} 1718:Doubling the cube 1657: 1650: 1635: 1612: 1597: 1568: 1561: 1541: 1515: 1508: 1488: 1444: 1431: 1404: 1369: 1348: 1324: 1309: 1258:similar triangles 1215: 1172: 1115: 1072: 1017:{\displaystyle E} 997:{\displaystyle S} 977:{\displaystyle F} 957:{\displaystyle F} 937:{\displaystyle E} 917:{\displaystyle S} 897:{\displaystyle S} 877:{\displaystyle S} 854:{\displaystyle S} 834:{\displaystyle C} 814:{\displaystyle A} 794:{\displaystyle S} 774:{\displaystyle S} 754:{\displaystyle S} 734:{\displaystyle S} 684: 641: 582: 539: 496: 436: 393: 336: 293: 236: 193: 64:similar triangles 28:intercept theorem 6930: 6896: 6895: 6883: 6882: 6881: 6657: 6656: 6644:Platonic Academy 6591:Problem II.8 of 6561:Crossbar theorem 6517:Thales's theorem 6457:Euclid's theorem 6427: 6426: 6344:Commensurability 6305:Axiomatic system 6253:Angle trisection 6218: 6208: 6170: 6160: 6150: 6140: 6116: 6106: 6089: 5652: 5645: 5638: 5629: 5628: 5607:Thales' Theorems 5557: 5541: 5519: 5483: 5450: 5420: 5410: 5404: 5389: 5383: 5376: 5370: 5355: 5349: 5334: 5328: 5306:Thales biography 5272: 5266: 5254: 5238: 5228: 5222: 5221: 5203: 5197: 5196: 5176: 5170: 5166: 5162: 5158: 5132: 5126: 5113:, Juan Läuchli: 5107: 5096: 5084: 5063: 5057: 5047: 5038: 5037: 5019: 4999: 4997: 4996: 4991: 4979: 4977: 4976: 4971: 4956: 4954: 4953: 4948: 4933: 4931: 4930: 4925: 4923: 4922: 4900: 4898: 4897: 4892: 4880: 4878: 4877: 4872: 4860: 4858: 4857: 4852: 4850: 4849: 4833: 4831: 4830: 4825: 4811: 4809: 4808: 4803: 4801: 4799: 4798: 4787: 4781: 4780: 4769: 4764: 4753: 4747: 4742: 4737: 4736: 4724: 4710: 4708: 4707: 4702: 4700: 4698: 4697: 4686: 4680: 4679: 4668: 4663: 4652: 4646: 4641: 4630: 4617: 4615: 4614: 4609: 4607: 4596: 4588: 4577: 4569: 4558: 4550: 4539: 4527: 4525: 4524: 4519: 4511: 4510: 4494: 4492: 4491: 4486: 4471: 4469: 4468: 4463: 4451: 4449: 4448: 4443: 4428: 4426: 4425: 4420: 4405: 4403: 4402: 4397: 4372: 4371: 4360: 4358: 4357: 4352: 4339: 4337: 4336: 4331: 4329: 4327: 4326: 4315: 4309: 4308: 4297: 4291: 4286: 4284: 4283: 4272: 4266: 4265: 4254: 4248: 4239: 4237: 4236: 4231: 4229: 4227: 4226: 4215: 4209: 4208: 4197: 4191: 4186: 4184: 4183: 4172: 4166: 4165: 4154: 4148: 4139: 4137: 4136: 4131: 4129: 4118: 4110: 4099: 4087: 4085: 4084: 4079: 4064: 4062: 4061: 4056: 4031: 4030: 4019: 4017: 4016: 4011: 3999: 3997: 3996: 3991: 3989: 3987: 3986: 3975: 3969: 3968: 3957: 3951: 3946: 3944: 3943: 3932: 3926: 3925: 3914: 3908: 3896: 3894: 3893: 3888: 3886: 3884: 3883: 3872: 3865: 3864: 3853: 3847: 3846: 3835: 3830: 3819: 3813: 3812: 3807: 3805: 3804: 3793: 3786: 3785: 3774: 3768: 3767: 3756: 3751: 3740: 3734: 3733: 3724: 3722: 3721: 3716: 3714: 3703: 3691: 3689: 3688: 3683: 3681: 3670: 3656: 3654: 3653: 3648: 3646: 3644: 3643: 3632: 3626: 3625: 3614: 3608: 3603: 3601: 3600: 3589: 3583: 3582: 3571: 3565: 3555: 3553: 3552: 3547: 3545: 3543: 3542: 3531: 3525: 3524: 3513: 3507: 3502: 3500: 3499: 3488: 3482: 3481: 3470: 3464: 3449: 3447: 3446: 3441: 3439: 3437: 3436: 3425: 3420: 3409: 3403: 3402: 3391: 3386: 3375: 3369: 3364: 3362: 3361: 3350: 3345: 3334: 3328: 3327: 3316: 3311: 3300: 3294: 3285: 3283: 3282: 3277: 3275: 3273: 3272: 3261: 3256: 3245: 3239: 3238: 3227: 3222: 3211: 3205: 3200: 3198: 3197: 3186: 3181: 3170: 3164: 3163: 3152: 3147: 3136: 3130: 3119: 3117: 3116: 3111: 3109: 3103: 3102: 3099: 3094: 3091: 3088: 3076: 3074: 3073: 3068: 3066: 3064: 3063: 3046: 3040: 3039: 3022: 3016: 3011: 3009: 3008: 2991: 2985: 2984: 2967: 2961: 2952: 2950: 2949: 2944: 2942: 2940: 2939: 2922: 2916: 2915: 2898: 2892: 2887: 2885: 2884: 2867: 2861: 2860: 2843: 2837: 2826: 2824: 2823: 2818: 2816: 2799: 2791: 2774: 2762: 2760: 2759: 2754: 2752: 2735: 2727: 2710: 2698: 2696: 2695: 2690: 2669: 2667: 2666: 2661: 2640: 2638: 2637: 2632: 2602: 2600: 2599: 2594: 2592: 2584: 2559: 2558: 2500: 2499: 2489: 2483: 2481: 2480: 2475: 2473: 2471: 2470: 2459: 2453: 2452: 2441: 2436: 2425: 2419: 2414: 2403: 2391: 2389: 2388: 2383: 2381: 2370: 2358: 2356: 2355: 2350: 2348: 2337: 2325: 2323: 2322: 2317: 2315: 2304: 2283: 2281: 2280: 2275: 2273: 2270: 2266: 2259: 2257: 2256: 2253: 2249: 2244: 2243: 2240: 2236: 2229: 2226: 2222: 2217: 2212: 2207: 2196: 2175: 2173: 2172: 2167: 2165: 2162: 2158: 2151: 2146: 2145: 2142: 2138: 2133: 2128: 2125: 2121: 2061:measuring pieces 2044: 2038: 2036: 2035: 2030: 2012: 2010: 2009: 2004: 2002: 1997: 1989: 1980: 1978: 1977: 1972: 1970: 1965: 1957: 1944: 1942: 1941: 1936: 1918: 1916: 1915: 1910: 1908: 1903: 1895: 1886: 1884: 1883: 1878: 1860: 1858: 1857: 1852: 1850: 1845: 1837: 1817: 1805: 1794: 1793: 1790: 1788: 1787: 1782: 1780: 1779: 1760: 1758: 1757: 1752: 1735:field operations 1731:field extensions 1691: 1684: 1682: 1681: 1676: 1674: 1666: 1658: 1656: 1652: 1651: 1643: 1637: 1636: 1628: 1621: 1614: 1613: 1605: 1599: 1598: 1590: 1574: 1569: 1567: 1563: 1562: 1554: 1547: 1543: 1542: 1534: 1521: 1516: 1514: 1510: 1509: 1501: 1494: 1490: 1489: 1481: 1468: 1459: 1457: 1456: 1451: 1446: 1445: 1437: 1429: 1425: 1417: 1406: 1405: 1397: 1381: 1379: 1378: 1373: 1371: 1370: 1362: 1350: 1349: 1341: 1326: 1325: 1317: 1311: 1310: 1302: 1235:Related concepts 1226: 1224: 1223: 1218: 1216: 1214: 1213: 1202: 1196: 1195: 1184: 1178: 1173: 1171: 1170: 1159: 1153: 1152: 1141: 1135: 1126: 1124: 1123: 1118: 1116: 1114: 1113: 1102: 1096: 1095: 1084: 1078: 1073: 1071: 1070: 1059: 1053: 1052: 1041: 1035: 1023: 1021: 1020: 1015: 1003: 1001: 1000: 995: 983: 981: 980: 975: 963: 961: 960: 955: 943: 941: 940: 935: 923: 921: 920: 915: 903: 901: 900: 895: 883: 881: 880: 875: 860: 858: 857: 852: 840: 838: 837: 832: 820: 818: 817: 812: 800: 798: 797: 792: 780: 778: 777: 772: 760: 758: 757: 752: 740: 738: 737: 732: 695: 693: 692: 687: 685: 683: 682: 671: 665: 664: 653: 647: 642: 640: 639: 628: 622: 621: 610: 604: 593: 591: 590: 585: 583: 581: 580: 569: 563: 562: 551: 545: 540: 538: 537: 526: 520: 519: 508: 502: 497: 495: 494: 483: 477: 476: 465: 459: 447: 445: 444: 439: 437: 435: 434: 423: 417: 416: 405: 399: 394: 392: 391: 380: 374: 373: 362: 356: 347: 345: 344: 339: 337: 335: 334: 323: 317: 316: 305: 299: 294: 292: 291: 280: 274: 273: 262: 256: 247: 245: 244: 239: 237: 235: 234: 223: 217: 216: 205: 199: 194: 192: 191: 180: 174: 173: 162: 156: 137: 133: 129: 32:Thales's theorem 30:, also known as 21:Thales's theorem 6938: 6937: 6933: 6932: 6931: 6929: 6928: 6927: 6908: 6907: 6906: 6901: 6890: 6879: 6877: 6866: 6832:Arabian/Islamic 6820: 6809:numeral systems 6698: 6648: 6618: 6566:Heron's formula 6544: 6526: 6418: 6414:Triangle center 6404:Regular polygon 6281:and definitions 6280: 6274: 6236: 6216: 6206: 6168: 6158: 6148: 6138: 6114: 6104: 6087: 6053: 6024:Theon of Smyrna 5669: 5661: 5656: 5613:Thales' Theorem 5590: 5575:Springer 2016, 5554: 5516: 5480: 5447: 5428: 5423: 5411: 5407: 5390: 5386: 5377: 5373: 5356: 5352: 5335: 5331: 5273: 5269: 5251: 5229: 5225: 5218: 5204: 5200: 5194: 5177: 5173: 5164: 5163:is parallel to 5160: 5149:| = | 5140: 5133: 5129: 5117:Springer 2016, 5108: 5099: 5081: 5064: 5060: 5048: 5041: 5034: 5020: 5013: 5009: 4985: 4982: 4981: 4962: 4959: 4958: 4939: 4936: 4935: 4918: 4914: 4906: 4903: 4902: 4886: 4883: 4882: 4866: 4863: 4862: 4845: 4841: 4839: 4836: 4835: 4819: 4816: 4815: 4813: 4794: 4783: 4782: 4776: 4765: 4760: 4749: 4748: 4746: 4738: 4732: 4728: 4720: 4718: 4715: 4714: 4713: 4711: 4693: 4682: 4681: 4675: 4664: 4659: 4648: 4647: 4645: 4637: 4626: 4624: 4621: 4620: 4619: 4603: 4592: 4584: 4573: 4565: 4554: 4546: 4535: 4533: 4530: 4529: 4506: 4502: 4500: 4497: 4496: 4477: 4474: 4473: 4457: 4454: 4453: 4434: 4431: 4430: 4411: 4408: 4407: 4388: 4385: 4384: 4370: 4346: 4343: 4342: 4322: 4311: 4310: 4304: 4293: 4292: 4290: 4279: 4268: 4267: 4261: 4250: 4249: 4247: 4245: 4242: 4241: 4222: 4211: 4210: 4204: 4193: 4192: 4190: 4179: 4168: 4167: 4161: 4150: 4149: 4147: 4145: 4142: 4141: 4125: 4114: 4106: 4095: 4093: 4090: 4089: 4070: 4067: 4066: 4047: 4044: 4043: 4029: 4004: 4001: 4000: 3982: 3971: 3970: 3964: 3953: 3952: 3950: 3939: 3928: 3927: 3921: 3910: 3909: 3907: 3904: 3901: 3900: 3879: 3868: 3867: 3860: 3849: 3848: 3842: 3831: 3826: 3815: 3814: 3811: 3800: 3789: 3788: 3781: 3770: 3769: 3763: 3752: 3747: 3736: 3735: 3732: 3730: 3727: 3726: 3710: 3699: 3697: 3694: 3693: 3677: 3666: 3664: 3661: 3660: 3639: 3628: 3627: 3621: 3610: 3609: 3607: 3596: 3585: 3584: 3578: 3567: 3566: 3564: 3561: 3558: 3557: 3538: 3527: 3526: 3520: 3509: 3508: 3506: 3495: 3484: 3483: 3477: 3466: 3465: 3463: 3460: 3457: 3456: 3432: 3421: 3416: 3405: 3404: 3398: 3387: 3382: 3371: 3370: 3368: 3357: 3346: 3341: 3330: 3329: 3323: 3312: 3307: 3296: 3295: 3293: 3291: 3288: 3287: 3268: 3257: 3252: 3241: 3240: 3234: 3223: 3218: 3207: 3206: 3204: 3193: 3182: 3177: 3166: 3165: 3159: 3148: 3143: 3132: 3131: 3129: 3127: 3124: 3123: 3098: 3090: 3089: 3086: 3084: 3081: 3080: 3059: 3042: 3041: 3035: 3018: 3017: 3015: 3004: 2987: 2986: 2980: 2963: 2962: 2960: 2958: 2955: 2954: 2935: 2918: 2917: 2911: 2894: 2893: 2891: 2880: 2863: 2862: 2856: 2839: 2838: 2836: 2834: 2831: 2830: 2812: 2795: 2787: 2770: 2768: 2765: 2764: 2748: 2731: 2723: 2706: 2704: 2701: 2700: 2675: 2672: 2671: 2646: 2643: 2642: 2614: 2611: 2610: 2588: 2580: 2578: 2575: 2574: 2557: 2549: 2537: 2495: 2466: 2455: 2454: 2448: 2437: 2432: 2421: 2420: 2418: 2410: 2399: 2397: 2394: 2393: 2377: 2366: 2364: 2361: 2360: 2344: 2333: 2331: 2328: 2327: 2311: 2300: 2298: 2295: 2294: 2290: 2269: 2252: 2245: 2239: 2225: 2218: 2216: 2197: 2195: 2187: 2184: 2183: 2161: 2141: 2134: 2132: 2124: 2110: 2107: 2106: 2079:Cheops' pyramid 2055: 2050: 2018: 2015: 2014: 1990: 1988: 1986: 1983: 1982: 1958: 1956: 1954: 1951: 1950: 1924: 1921: 1920: 1896: 1894: 1892: 1889: 1888: 1866: 1863: 1862: 1838: 1836: 1834: 1831: 1830: 1827: 1772: 1768: 1766: 1763: 1762: 1746: 1743: 1742: 1702: 1697: 1670: 1662: 1642: 1641: 1627: 1626: 1622: 1604: 1603: 1589: 1588: 1575: 1573: 1553: 1552: 1548: 1533: 1532: 1522: 1520: 1500: 1499: 1495: 1480: 1479: 1469: 1467: 1465: 1462: 1461: 1436: 1435: 1421: 1413: 1396: 1395: 1387: 1384: 1383: 1361: 1360: 1340: 1339: 1316: 1315: 1301: 1300: 1289: 1286: 1285: 1284:(in particular 1280:concerning the 1270: 1242: 1237: 1209: 1198: 1197: 1191: 1180: 1179: 1177: 1166: 1155: 1154: 1148: 1137: 1136: 1134: 1132: 1129: 1128: 1109: 1098: 1097: 1091: 1080: 1079: 1077: 1066: 1055: 1054: 1048: 1037: 1036: 1034: 1032: 1029: 1028: 1009: 1006: 1005: 989: 986: 985: 969: 966: 965: 949: 946: 945: 929: 926: 925: 909: 906: 905: 889: 886: 885: 869: 866: 865: 846: 843: 842: 826: 823: 822: 806: 803: 802: 786: 783: 782: 766: 763: 762: 746: 743: 742: 726: 723: 722: 703: 678: 667: 666: 660: 649: 648: 646: 635: 624: 623: 617: 606: 605: 603: 601: 598: 597: 576: 565: 564: 558: 547: 546: 544: 533: 522: 521: 515: 504: 503: 501: 490: 479: 478: 472: 461: 460: 458: 456: 453: 452: 451: 430: 419: 418: 412: 401: 400: 398: 387: 376: 375: 369: 358: 357: 355: 353: 350: 349: 330: 319: 318: 312: 301: 300: 298: 287: 276: 275: 269: 258: 257: 255: 253: 250: 249: 230: 219: 218: 212: 201: 200: 198: 187: 176: 175: 169: 158: 157: 155: 153: 150: 149: 148: 135: 134:is parallel to 131: 120:| = | 111: 97: 24: 17: 12: 11: 5: 6936: 6926: 6925: 6920: 6903: 6902: 6875: 6872: 6871: 6868: 6867: 6865: 6864: 6859: 6854: 6849: 6844: 6839: 6834: 6828: 6826: 6825:Other cultures 6822: 6821: 6819: 6818: 6817: 6816: 6806: 6805: 6804: 6794: 6793: 6792: 6782: 6781: 6780: 6770: 6769: 6768: 6758: 6757: 6756: 6746: 6745: 6744: 6734: 6733: 6732: 6722: 6721: 6720: 6706: 6704: 6700: 6699: 6697: 6696: 6691: 6686: 6681: 6676: 6674:Greek numerals 6671: 6669:Attic numerals 6666: 6660: 6654: 6650: 6649: 6647: 6646: 6641: 6636: 6630: 6628: 6624: 6623: 6620: 6619: 6617: 6616: 6611: 6606: 6601: 6596: 6588: 6583: 6578: 6573: 6568: 6563: 6558: 6552: 6550: 6546: 6545: 6543: 6542: 6536: 6534: 6528: 6527: 6525: 6524: 6519: 6514: 6509: 6504: 6499: 6497:Law of cosines 6494: 6489: 6484: 6479: 6474: 6469: 6464: 6459: 6454: 6449: 6444: 6438: 6436: 6424: 6420: 6419: 6417: 6416: 6411: 6406: 6401: 6396: 6391: 6389:Platonic solid 6386: 6381: 6376: 6371: 6369:Greek numerals 6366: 6361: 6356: 6351: 6346: 6341: 6336: 6335: 6334: 6329: 6319: 6314: 6313: 6312: 6302: 6301: 6300: 6295: 6284: 6282: 6276: 6275: 6273: 6272: 6267: 6266: 6265: 6260: 6255: 6244: 6242: 6238: 6237: 6235: 6234: 6227: 6220: 6210: 6200: 6197:Planisphaerium 6193: 6186: 6179: 6172: 6162: 6152: 6142: 6132: 6125: 6118: 6108: 6098: 6091: 6081: 6074: 6069: 6061: 6059: 6055: 6054: 6052: 6051: 6046: 6041: 6036: 6031: 6026: 6021: 6016: 6011: 6006: 6001: 5996: 5991: 5986: 5981: 5976: 5971: 5966: 5961: 5956: 5951: 5946: 5941: 5936: 5931: 5926: 5921: 5916: 5911: 5906: 5901: 5896: 5891: 5886: 5881: 5876: 5871: 5866: 5861: 5856: 5851: 5846: 5841: 5836: 5831: 5826: 5821: 5816: 5811: 5806: 5801: 5796: 5791: 5786: 5781: 5776: 5771: 5766: 5761: 5756: 5751: 5746: 5741: 5736: 5731: 5726: 5721: 5716: 5711: 5706: 5701: 5696: 5691: 5686: 5681: 5675: 5673: 5667:Mathematicians 5663: 5662: 5655: 5654: 5647: 5640: 5632: 5626: 5625: 5620: 5602: 5589: 5588:External links 5586: 5585: 5584: 5569: 5552: 5531: 5514: 5495: 5478: 5466:Agricola, Ilka 5462: 5445: 5427: 5424: 5422: 5421: 5405: 5391:Gilles Dowek: 5384: 5371: 5350: 5329: 5267: 5249: 5223: 5216: 5198: 5192: 5171: 5127: 5097: 5079: 5067:Agricola, Ilka 5058: 5039: 5032: 5010: 5008: 5005: 5002: 5001: 4989: 4969: 4966: 4946: 4943: 4921: 4917: 4913: 4910: 4901:, which means 4890: 4870: 4848: 4844: 4823: 4797: 4793: 4790: 4786: 4779: 4775: 4772: 4768: 4763: 4759: 4756: 4752: 4745: 4741: 4735: 4731: 4727: 4723: 4696: 4692: 4689: 4685: 4678: 4674: 4671: 4667: 4662: 4658: 4655: 4651: 4644: 4640: 4636: 4633: 4629: 4606: 4602: 4599: 4595: 4591: 4587: 4583: 4580: 4576: 4572: 4568: 4564: 4561: 4557: 4553: 4549: 4545: 4542: 4538: 4517: 4514: 4509: 4505: 4484: 4481: 4461: 4441: 4438: 4418: 4415: 4395: 4392: 4369: 4366: 4363: 4362: 4350: 4325: 4321: 4318: 4314: 4307: 4303: 4300: 4296: 4289: 4282: 4278: 4275: 4271: 4264: 4260: 4257: 4253: 4240:and therefore 4225: 4221: 4218: 4214: 4207: 4203: 4200: 4196: 4189: 4182: 4178: 4175: 4171: 4164: 4160: 4157: 4153: 4128: 4124: 4121: 4117: 4113: 4109: 4105: 4102: 4098: 4077: 4074: 4054: 4051: 4028: 4025: 4022: 4021: 4009: 3985: 3981: 3978: 3974: 3967: 3963: 3960: 3956: 3949: 3942: 3938: 3935: 3931: 3924: 3920: 3917: 3913: 3882: 3878: 3875: 3871: 3863: 3859: 3856: 3852: 3845: 3841: 3838: 3834: 3829: 3825: 3822: 3818: 3810: 3803: 3799: 3796: 3792: 3784: 3780: 3777: 3773: 3766: 3762: 3759: 3755: 3750: 3746: 3743: 3739: 3713: 3709: 3706: 3702: 3680: 3676: 3673: 3669: 3642: 3638: 3635: 3631: 3624: 3620: 3617: 3613: 3606: 3599: 3595: 3592: 3588: 3581: 3577: 3574: 3570: 3541: 3537: 3534: 3530: 3523: 3519: 3516: 3512: 3505: 3498: 3494: 3491: 3487: 3480: 3476: 3473: 3469: 3435: 3431: 3428: 3424: 3419: 3415: 3412: 3408: 3401: 3397: 3394: 3390: 3385: 3381: 3378: 3374: 3367: 3360: 3356: 3353: 3349: 3344: 3340: 3337: 3333: 3326: 3322: 3319: 3315: 3310: 3306: 3303: 3299: 3271: 3267: 3264: 3260: 3255: 3251: 3248: 3244: 3237: 3233: 3230: 3226: 3221: 3217: 3214: 3210: 3203: 3196: 3192: 3189: 3185: 3180: 3176: 3173: 3169: 3162: 3158: 3155: 3151: 3146: 3142: 3139: 3135: 3106: 3097: 3062: 3058: 3055: 3052: 3049: 3045: 3038: 3034: 3031: 3028: 3025: 3021: 3014: 3007: 3003: 3000: 2997: 2994: 2990: 2983: 2979: 2976: 2973: 2970: 2966: 2938: 2934: 2931: 2928: 2925: 2921: 2914: 2910: 2907: 2904: 2901: 2897: 2890: 2883: 2879: 2876: 2873: 2870: 2866: 2859: 2855: 2852: 2849: 2846: 2842: 2815: 2811: 2808: 2805: 2802: 2798: 2794: 2790: 2786: 2783: 2780: 2777: 2773: 2763:and therefore 2751: 2747: 2744: 2741: 2738: 2734: 2730: 2726: 2722: 2719: 2716: 2713: 2709: 2688: 2685: 2682: 2679: 2659: 2656: 2653: 2650: 2630: 2627: 2624: 2621: 2618: 2591: 2587: 2583: 2556: 2553: 2548: 2545: 2536: 2533: 2530: 2529: 2517: 2494: 2491: 2469: 2465: 2462: 2458: 2451: 2447: 2444: 2440: 2435: 2431: 2428: 2424: 2417: 2413: 2409: 2406: 2402: 2380: 2376: 2373: 2369: 2347: 2343: 2340: 2336: 2314: 2310: 2307: 2303: 2289: 2286: 2285: 2284: 2265: 2262: 2248: 2235: 2232: 2221: 2215: 2210: 2206: 2203: 2200: 2194: 2191: 2177: 2176: 2157: 2154: 2149: 2137: 2131: 2120: 2117: 2114: 2100: 2099: 2096: 2093: 2090: 2054: 2051: 2049: 2046: 2028: 2025: 2022: 2000: 1996: 1993: 1968: 1964: 1961: 1934: 1931: 1928: 1906: 1902: 1899: 1876: 1873: 1870: 1848: 1844: 1841: 1826: 1823: 1820: 1819: 1807: 1778: 1775: 1771: 1750: 1726: 1725: 1720: 1715: 1701: 1698: 1696: 1693: 1673: 1669: 1665: 1661: 1655: 1649: 1646: 1640: 1634: 1631: 1625: 1620: 1617: 1611: 1608: 1602: 1596: 1593: 1587: 1584: 1581: 1578: 1572: 1566: 1560: 1557: 1551: 1546: 1540: 1537: 1531: 1528: 1525: 1519: 1513: 1507: 1504: 1498: 1493: 1487: 1484: 1478: 1475: 1472: 1449: 1443: 1440: 1434: 1428: 1424: 1420: 1416: 1412: 1409: 1403: 1400: 1394: 1391: 1368: 1365: 1359: 1356: 1353: 1347: 1344: 1338: 1335: 1332: 1329: 1323: 1320: 1314: 1308: 1305: 1299: 1296: 1293: 1269: 1266: 1241: 1238: 1236: 1233: 1228: 1227: 1212: 1208: 1205: 1201: 1194: 1190: 1187: 1183: 1176: 1169: 1165: 1162: 1158: 1151: 1147: 1144: 1140: 1112: 1108: 1105: 1101: 1094: 1090: 1087: 1083: 1076: 1069: 1065: 1062: 1058: 1051: 1047: 1044: 1040: 1013: 993: 973: 953: 933: 913: 893: 873: 850: 830: 810: 790: 770: 750: 730: 702: 699: 698: 697: 681: 677: 674: 670: 663: 659: 656: 652: 645: 638: 634: 631: 627: 620: 616: 613: 609: 594: 579: 575: 572: 568: 561: 557: 554: 550: 543: 536: 532: 529: 525: 518: 514: 511: 507: 500: 493: 489: 486: 482: 475: 471: 468: 464: 448: 433: 429: 426: 422: 415: 411: 408: 404: 397: 390: 386: 383: 379: 372: 368: 365: 361: 333: 329: 326: 322: 315: 311: 308: 304: 297: 290: 286: 283: 279: 272: 268: 265: 261: 233: 229: 226: 222: 215: 211: 208: 204: 197: 190: 186: 183: 179: 172: 168: 165: 161: 96: 93: 15: 9: 6: 4: 3: 2: 6935: 6924: 6921: 6919: 6916: 6915: 6913: 6900: 6899: 6894: 6887: 6886: 6873: 6863: 6860: 6858: 6855: 6853: 6850: 6848: 6845: 6843: 6840: 6838: 6835: 6833: 6830: 6829: 6827: 6823: 6815: 6812: 6811: 6810: 6807: 6803: 6800: 6799: 6798: 6795: 6791: 6788: 6787: 6786: 6783: 6779: 6776: 6775: 6774: 6771: 6767: 6764: 6763: 6762: 6759: 6755: 6752: 6751: 6750: 6747: 6743: 6740: 6739: 6738: 6735: 6731: 6728: 6727: 6726: 6723: 6719: 6715: 6714: 6713: 6712: 6708: 6707: 6705: 6701: 6695: 6692: 6690: 6687: 6685: 6682: 6680: 6677: 6675: 6672: 6670: 6667: 6665: 6662: 6661: 6658: 6655: 6651: 6645: 6642: 6640: 6637: 6635: 6632: 6631: 6629: 6625: 6615: 6612: 6610: 6607: 6605: 6602: 6600: 6597: 6595: 6594: 6589: 6587: 6584: 6582: 6579: 6577: 6574: 6572: 6569: 6567: 6564: 6562: 6559: 6557: 6554: 6553: 6551: 6547: 6541: 6538: 6537: 6535: 6533: 6529: 6523: 6520: 6518: 6515: 6513: 6510: 6508: 6505: 6503: 6502:Pons asinorum 6500: 6498: 6495: 6493: 6490: 6488: 6485: 6483: 6480: 6478: 6475: 6473: 6472:Hinge theorem 6470: 6468: 6465: 6463: 6460: 6458: 6455: 6453: 6450: 6448: 6445: 6443: 6440: 6439: 6437: 6435: 6434: 6428: 6425: 6421: 6415: 6412: 6410: 6407: 6405: 6402: 6400: 6397: 6395: 6392: 6390: 6387: 6385: 6382: 6380: 6377: 6375: 6372: 6370: 6367: 6365: 6362: 6360: 6357: 6355: 6352: 6350: 6347: 6345: 6342: 6340: 6337: 6333: 6330: 6328: 6325: 6324: 6323: 6320: 6318: 6315: 6311: 6308: 6307: 6306: 6303: 6299: 6296: 6294: 6291: 6290: 6289: 6286: 6285: 6283: 6277: 6271: 6268: 6264: 6261: 6259: 6256: 6254: 6251: 6250: 6249: 6246: 6245: 6243: 6239: 6233: 6232: 6228: 6226: 6225: 6221: 6219: 6215: 6211: 6209: 6205: 6201: 6199: 6198: 6194: 6192: 6191: 6187: 6185: 6184: 6180: 6178: 6177: 6173: 6171: 6167: 6163: 6161: 6157: 6153: 6151: 6147: 6143: 6141: 6139:(Aristarchus) 6137: 6133: 6131: 6130: 6126: 6124: 6123: 6119: 6117: 6113: 6109: 6107: 6103: 6099: 6097: 6096: 6092: 6090: 6086: 6082: 6080: 6079: 6075: 6073: 6070: 6068: 6067: 6063: 6062: 6060: 6056: 6050: 6047: 6045: 6044:Zeno of Sidon 6042: 6040: 6037: 6035: 6032: 6030: 6027: 6025: 6022: 6020: 6017: 6015: 6012: 6010: 6007: 6005: 6002: 6000: 5997: 5995: 5992: 5990: 5987: 5985: 5982: 5980: 5977: 5975: 5972: 5970: 5967: 5965: 5962: 5960: 5957: 5955: 5952: 5950: 5947: 5945: 5942: 5940: 5937: 5935: 5932: 5930: 5927: 5925: 5922: 5920: 5917: 5915: 5912: 5910: 5907: 5905: 5902: 5900: 5897: 5895: 5892: 5890: 5887: 5885: 5882: 5880: 5877: 5875: 5872: 5870: 5867: 5865: 5862: 5860: 5857: 5855: 5852: 5850: 5847: 5845: 5842: 5840: 5837: 5835: 5832: 5830: 5827: 5825: 5822: 5820: 5817: 5815: 5812: 5810: 5807: 5805: 5802: 5800: 5797: 5795: 5792: 5790: 5787: 5785: 5782: 5780: 5777: 5775: 5772: 5770: 5767: 5765: 5762: 5760: 5757: 5755: 5752: 5750: 5747: 5745: 5742: 5740: 5737: 5735: 5732: 5730: 5727: 5725: 5722: 5720: 5717: 5715: 5712: 5710: 5707: 5705: 5702: 5700: 5697: 5695: 5692: 5690: 5687: 5685: 5682: 5680: 5677: 5676: 5674: 5672: 5668: 5664: 5660: 5653: 5648: 5646: 5641: 5639: 5634: 5633: 5630: 5624: 5621: 5619: 5615: 5614: 5609: 5608: 5603: 5601: 5597: 5596: 5592: 5591: 5582: 5581:9783662530344 5578: 5574: 5570: 5567: 5563: 5562: 5555: 5549: 5545: 5540: 5539: 5532: 5529: 5525: 5524: 5517: 5511: 5507: 5503: 5502: 5496: 5493: 5489: 5488: 5481: 5479:0-8218-4347-8 5475: 5471: 5467: 5463: 5460: 5456: 5455: 5448: 5446:9780826473622 5442: 5438: 5434: 5430: 5429: 5419: 5415: 5409: 5402: 5401:9780521118019 5398: 5394: 5388: 5381: 5375: 5368: 5364: 5360: 5354: 5348:, pp. 214–217 5347: 5346:9783030409746 5343: 5339: 5333: 5326: 5324: 5319: 5317: 5312: 5308: 5307: 5302: 5298: 5294: 5290: 5286: 5281: 5277: 5271: 5264: 5260: 5259: 5252: 5246: 5242: 5237: 5236: 5227: 5219: 5217:3-528-07243-1 5213: 5209: 5202: 5195: 5193:0-486-42515-0 5189: 5185: 5181: 5175: 5156: 5152: 5148: 5144: 5138: 5131: 5124: 5123:9783662530344 5120: 5116: 5112: 5106: 5104: 5102: 5094: 5090: 5089: 5082: 5080:0-8218-4347-8 5076: 5072: 5068: 5062: 5055: 5051: 5050:Strahlensätze 5046: 5044: 5035: 5033:3-506-99189-2 5029: 5025: 5018: 5016: 5011: 5000: 4987: 4967: 4964: 4944: 4941: 4919: 4915: 4911: 4908: 4888: 4868: 4846: 4842: 4821: 4791: 4788: 4773: 4770: 4757: 4754: 4743: 4733: 4729: 4725: 4690: 4687: 4672: 4669: 4656: 4653: 4642: 4634: 4631: 4600: 4597: 4589: 4581: 4578: 4570: 4562: 4559: 4551: 4543: 4540: 4515: 4512: 4507: 4503: 4482: 4479: 4459: 4439: 4436: 4416: 4413: 4393: 4390: 4378: 4373: 4361: 4348: 4340: 4319: 4316: 4301: 4298: 4287: 4276: 4273: 4258: 4255: 4219: 4216: 4201: 4198: 4187: 4176: 4173: 4158: 4155: 4122: 4119: 4111: 4103: 4100: 4075: 4072: 4052: 4049: 4037: 4032: 4020: 4007: 3979: 3976: 3961: 3958: 3947: 3936: 3933: 3918: 3915: 3897: 3876: 3873: 3857: 3854: 3839: 3836: 3823: 3820: 3808: 3797: 3794: 3778: 3775: 3760: 3757: 3744: 3741: 3707: 3704: 3674: 3671: 3657: 3636: 3633: 3618: 3615: 3604: 3593: 3590: 3575: 3572: 3535: 3532: 3517: 3514: 3503: 3492: 3489: 3474: 3471: 3453: 3450: 3429: 3426: 3413: 3410: 3395: 3392: 3379: 3376: 3365: 3354: 3351: 3338: 3335: 3320: 3317: 3304: 3301: 3265: 3262: 3249: 3246: 3231: 3228: 3215: 3212: 3201: 3190: 3187: 3174: 3171: 3156: 3153: 3140: 3137: 3121: 3104: 3095: 3077: 3056: 3053: 3050: 3032: 3029: 3026: 3012: 3001: 2998: 2995: 2977: 2974: 2971: 2932: 2929: 2926: 2908: 2905: 2902: 2888: 2877: 2874: 2871: 2853: 2850: 2847: 2828: 2809: 2806: 2803: 2792: 2784: 2781: 2778: 2745: 2742: 2739: 2728: 2720: 2717: 2714: 2686: 2683: 2680: 2657: 2654: 2651: 2628: 2625: 2622: 2619: 2616: 2608: 2604: 2585: 2572: 2565: 2560: 2552: 2544: 2542: 2525: 2521: 2513: 2509: 2507: 2501: 2498: 2490: 2488: 2463: 2460: 2445: 2442: 2429: 2426: 2415: 2407: 2404: 2374: 2371: 2341: 2338: 2308: 2305: 2263: 2260: 2246: 2233: 2230: 2219: 2213: 2208: 2204: 2201: 2198: 2192: 2189: 2182: 2181: 2180: 2155: 2152: 2147: 2135: 2129: 2118: 2115: 2112: 2105: 2104: 2103: 2097: 2094: 2091: 2088: 2087: 2086: 2082: 2080: 2076: 2067: 2059: 2045: 2043: 2026: 2023: 2020: 1994: 1991: 1962: 1959: 1948: 1932: 1929: 1926: 1900: 1897: 1874: 1871: 1868: 1842: 1839: 1818: 1816: 1812: 1806: 1804: 1800: 1795: 1792: 1776: 1773: 1769: 1748: 1740: 1736: 1732: 1724: 1721: 1719: 1716: 1714: 1711: 1710: 1709: 1707: 1692: 1690: 1685: 1667: 1659: 1644: 1638: 1629: 1606: 1600: 1591: 1582: 1579: 1570: 1555: 1535: 1529: 1526: 1517: 1502: 1482: 1476: 1473: 1438: 1426: 1418: 1410: 1398: 1392: 1363: 1357: 1354: 1351: 1342: 1336: 1333: 1330: 1318: 1312: 1303: 1294: 1291: 1283: 1279: 1275: 1265: 1263: 1259: 1255: 1246: 1232: 1206: 1203: 1188: 1185: 1174: 1163: 1160: 1145: 1142: 1106: 1103: 1088: 1085: 1074: 1063: 1060: 1045: 1042: 1027: 1026: 1025: 1011: 991: 971: 964:, such that 951: 931: 911: 891: 871: 862: 848: 828: 808: 788: 768: 748: 728: 715: 707: 675: 672: 657: 654: 643: 632: 629: 614: 611: 595: 573: 570: 555: 552: 541: 530: 527: 512: 509: 498: 487: 484: 469: 466: 449: 427: 424: 409: 406: 395: 384: 381: 366: 363: 327: 324: 309: 306: 295: 284: 281: 266: 263: 227: 224: 209: 206: 195: 184: 181: 166: 163: 146: 145: 144: 127: 123: 119: 115: 109: 101: 92: 90: 89: 84: 80: 76: 72: 69: 65: 61: 57: 53: 52:line segments 49: 45: 41: 37: 33: 29: 22: 6889: 6876: 6718:Thomas Heath 6709: 6592: 6576:Law of sines 6481: 6432: 6364:Golden ratio 6229: 6222: 6213: 6207:(Theodosius) 6203: 6195: 6188: 6181: 6174: 6165: 6155: 6149:(Hipparchus) 6145: 6135: 6127: 6120: 6111: 6101: 6093: 6088:(Apollonius) 6084: 6076: 6064: 6039:Zeno of Elea 5799:Eratosthenes 5789:Dionysodorus 5618:Cut-the-Knot 5612: 5606: 5594: 5572: 5566:Google Books 5559: 5537: 5528:Google Books 5526:, p. 34, at 5521: 5500: 5492:Google Books 5490:, p. 10, at 5485: 5469: 5459:Google Books 5457:, p. 84, at 5452: 5436: 5433:French, Doug 5413: 5408: 5392: 5387: 5379: 5374: 5358: 5353: 5337: 5332: 5322: 5315: 5305: 5303:". (Source: 5300: 5295:". However, 5292: 5288: 5270: 5263:Google Books 5256: 5234: 5226: 5207: 5201: 5183: 5174: 5154: 5150: 5146: 5142: 5130: 5114: 5093:Google Books 5091:, p. 10, at 5086: 5070: 5061: 5053: 5049: 5023: 4382: 4341: 4041: 3898: 3658: 3454: 3451: 3122: 3078: 2829: 2606: 2605: 2570: 2569: 2550: 2538: 2519: 2503: 2496: 2291: 2178: 2101: 2083: 2072: 1946: 1828: 1810: 1809: 1798: 1797: 1727: 1703: 1695:Applications 1686: 1274:vector space 1272:In a normed 1271: 1251: 1229: 863: 720: 141: 125: 121: 117: 113: 86: 39: 35: 31: 27: 25: 6785:mathematics 6593:Arithmetica 6190:Ostomachion 6159:(Autolycus) 6078:Arithmetica 5854:Hippocrates 5784:Dinostratus 5769:Dicaearchus 5699:Aristarchus 5564:, p. 3, at 5561:online copy 5523:online copy 5487:online copy 5454:online copy 5403:, pp. 17-18 5369:, pp. 27-36 5261:, p. 7, at 5258:online copy 5088:online copy 4472:intersects 75:Babylonians 6912:Categories 6837:Babylonian 6737:arithmetic 6703:History of 6532:Apollonius 6217:(Menelaus) 6176:On Spirals 6095:Catoptrics 6034:Xenocrates 6029:Thymaridas 6014:Theodosius 5999:Theaetetus 5979:Simplicius 5969:Pythagoras 5954:Posidonius 5939:Philonides 5899:Nicomachus 5894:Metrodorus 5884:Menaechmus 5839:Hipparchus 5829:Heliodorus 5779:Diophantus 5764:Democritus 5744:Chrysippus 5714:Archimedes 5709:Apollonius 5679:Anaxagoras 5671:(timeline) 5600:PlanetMath 5426:References 5285:Hieronymus 1262:conversely 1254:similarity 6298:Inscribed 6058:Treatises 6049:Zenodorus 6009:Theodorus 5984:Sosigenes 5929:Philolaus 5914:Oenopides 5909:Nicoteles 5904:Nicomedes 5864:Hypsicles 5759:Ctesibius 5749:Cleomedes 5734:Callippus 5719:Autolycus 5704:Aristotle 5684:Anthemius 5182:(2003) , 4988:◻ 4513:≠ 4349:◻ 4008:◻ 3096:⋅ 3048:△ 3024:△ 2993:△ 2969:△ 2924:△ 2900:△ 2869:△ 2845:△ 2801:△ 2776:△ 2737:△ 2712:△ 2678:△ 2649:△ 2623:∥ 2586:… 2571:Notation: 2231:⋅ 2202:⋅ 1999:¯ 1967:¯ 1905:¯ 1847:¯ 1774:− 1668:λ 1654:‖ 1648:→ 1633:→ 1624:‖ 1619:‖ 1610:→ 1595:→ 1583:⋅ 1580:λ 1577:‖ 1565:‖ 1559:→ 1550:‖ 1545:‖ 1539:→ 1530:⋅ 1527:λ 1524:‖ 1512:‖ 1506:→ 1497:‖ 1492:‖ 1486:→ 1477:⋅ 1474:λ 1471:‖ 1448:‖ 1442:→ 1433:‖ 1427:⋅ 1419:λ 1408:‖ 1402:→ 1393:λ 1390:‖ 1367:→ 1358:⋅ 1355:λ 1346:→ 1337:⋅ 1334:λ 1322:→ 1307:→ 1295:⋅ 1292:λ 79:Egyptians 60:parallels 6862:Japanese 6847:Egyptian 6790:timeline 6778:timeline 6766:timeline 6761:geometry 6754:timeline 6749:calculus 6742:timeline 6730:timeline 6433:Elements 6279:Concepts 6241:Problems 6214:Spherics 6204:Spherics 6169:(Euclid) 6115:(Euclid) 6112:Elements 6105:(Euclid) 6066:Almagest 5974:Serenus 5949:Porphyry 5889:Menelaus 5844:Hippasus 5819:Eutocius 5794:Domninus 5689:Archytas 5435:(2004). 5311:MacTutor 5297:Plutarch 4528:. Since 4452:through 3725:in (a): 3556:and (b) 3100:altitude 3092:baseline 88:Elements 6842:Chinese 6797:numbers 6725:algebra 6653:Related 6627:Centers 6423:Results 6293:Central 5964:Ptolemy 5959:Proclus 5924:Perseus 5879:Marinus 5859:Hypatia 5849:Hippias 5824:Geminus 5814:Eudoxus 5804:Eudemus 5774:Diocles 5309:of the 5208:Algebra 4383:Assume 4368:Claim 3 4027:Claim 2 2555:Claim 1 2039:ratio. 44:theorem 6857:Indian 6634:Cyrene 6166:Optics 6085:Conics 6004:Theano 5994:Thales 5989:Sporus 5934:Philon 5919:Pappus 5809:Euclid 5739:Carpus 5729:Bryson 5579:  5550:  5512:  5476:  5443:  5399:  5365:  5344:  5318:, 147A 5247:  5214:  5190:  5157:| 5141:| 5121:  5077:  5052:. In: 5030:  2609:Since 2607:Proof: 2267:  2250:  2237:  2223:  2159:  2139:  2122:  2075:Thales 1430:  1278:axioms 1276:, the 128:| 112:| 83:Euclid 71:Thales 6852:Incan 6773:logic 6549:Other 6317:Chord 6310:Axiom 6288:Angle 5944:Plato 5834:Heron 5754:Conon 5418:JSTOR 5280:Pliny 5007:Notes 2547:Proof 2264:146.7 2013:in a 1861:in a 1004:than 6814:list 6102:Data 5874:Leon 5724:Bion 5577:ISBN 5548:ISBN 5546:–7. 5510:ISBN 5474:ISBN 5441:ISBN 5397:ISBN 5363:ISBN 5342:ISBN 5320:and 5278:and 5245:ISBN 5212:ISBN 5188:ISBN 5119:ISBN 5075:ISBN 5028:ISBN 4957:and 4834:and 4406:and 3692:and 3455:(a) 3286:and 2953:and 2670:and 2220:1.63 1382:and 944:and 821:and 77:and 56:rays 26:The 6716:by 6430:In 5616:at 5598:at 4814:So 4495:in 2508:). 2234:180 2156:180 2136:230 841:at 85:'s 46:in 38:or 6914:: 5508:. 5506:34 5243:. 5165:BD 5161:AC 5155:SD 5151:SC 5147:SB 5143:SA 5100:^ 5042:^ 5014:^ 4812:. 2484:. 2119:65 1708:: 1127:, 348:, 248:, 136:BD 132:AC 126:BD 122:AC 118:SB 114:SA 91:. 34:, 5651:e 5644:t 5637:v 5568:) 5558:( 5556:. 5544:3 5530:) 5520:( 5518:. 5494:) 5484:( 5482:. 5461:) 5451:( 5449:. 5327:) 5265:) 5255:( 5253:. 5241:7 5220:. 5167:. 5095:) 5085:( 5083:. 5036:. 4968:D 4965:B 4945:C 4942:A 4920:0 4916:B 4912:= 4909:B 4889:S 4869:S 4847:0 4843:B 4822:B 4796:| 4792:C 4789:S 4785:| 4778:| 4774:A 4771:S 4767:| 4762:| 4758:D 4755:S 4751:| 4744:= 4740:| 4734:0 4730:B 4726:S 4722:| 4695:| 4691:C 4688:S 4684:| 4677:| 4673:A 4670:S 4666:| 4661:| 4657:D 4654:S 4650:| 4643:= 4639:| 4635:B 4632:S 4628:| 4605:| 4601:C 4598:S 4594:| 4590:: 4586:| 4582:D 4579:S 4575:| 4571:= 4567:| 4563:A 4560:S 4556:| 4552:: 4548:| 4544:B 4541:S 4537:| 4516:B 4508:0 4504:B 4483:A 4480:S 4460:D 4440:C 4437:A 4417:D 4414:B 4394:C 4391:A 4324:| 4320:D 4317:B 4313:| 4306:| 4302:C 4299:A 4295:| 4288:= 4281:| 4277:B 4274:S 4270:| 4263:| 4259:A 4256:S 4252:| 4224:| 4220:D 4217:B 4213:| 4206:| 4202:G 4199:D 4195:| 4188:= 4181:| 4177:B 4174:S 4170:| 4163:| 4159:A 4156:S 4152:| 4127:| 4123:G 4120:D 4116:| 4112:= 4108:| 4104:C 4101:A 4097:| 4076:D 4073:B 4053:D 4050:S 3984:| 3980:B 3977:A 3973:| 3966:| 3962:B 3959:S 3955:| 3948:= 3941:| 3937:D 3934:C 3930:| 3923:| 3919:D 3916:S 3912:| 3881:| 3877:B 3874:A 3870:| 3862:| 3858:D 3855:S 3851:| 3844:| 3840:C 3837:S 3833:| 3828:| 3824:B 3821:S 3817:| 3809:= 3802:| 3798:D 3795:C 3791:| 3783:| 3779:B 3776:S 3772:| 3765:| 3761:D 3758:S 3754:| 3749:| 3745:A 3742:S 3738:| 3712:| 3708:C 3705:S 3701:| 3679:| 3675:A 3672:S 3668:| 3641:| 3637:B 3634:S 3630:| 3623:| 3619:A 3616:S 3612:| 3605:= 3598:| 3594:D 3591:S 3587:| 3580:| 3576:C 3573:S 3569:| 3540:| 3536:B 3533:A 3529:| 3522:| 3518:A 3515:S 3511:| 3504:= 3497:| 3493:D 3490:C 3486:| 3479:| 3475:C 3472:S 3468:| 3434:| 3430:C 3427:E 3423:| 3418:| 3414:B 3411:S 3407:| 3400:| 3396:C 3393:E 3389:| 3384:| 3380:A 3377:S 3373:| 3366:= 3359:| 3355:F 3352:A 3348:| 3343:| 3339:D 3336:S 3332:| 3325:| 3321:F 3318:A 3314:| 3309:| 3305:C 3302:S 3298:| 3270:| 3266:C 3263:E 3259:| 3254:| 3250:B 3247:A 3243:| 3236:| 3232:C 3229:E 3225:| 3220:| 3216:A 3213:S 3209:| 3202:= 3195:| 3191:F 3188:A 3184:| 3179:| 3175:D 3172:C 3168:| 3161:| 3157:F 3154:A 3150:| 3145:| 3141:C 3138:S 3134:| 3105:2 3061:| 3057:B 3054:C 3051:S 3044:| 3037:| 3033:A 3030:C 3027:S 3020:| 3013:= 3006:| 3002:A 2999:D 2996:S 2989:| 2982:| 2978:A 2975:C 2972:S 2965:| 2937:| 2933:A 2930:B 2927:C 2920:| 2913:| 2909:A 2906:C 2903:S 2896:| 2889:= 2882:| 2878:A 2875:D 2872:C 2865:| 2858:| 2854:A 2851:C 2848:S 2841:| 2814:| 2810:A 2807:D 2804:S 2797:| 2793:= 2789:| 2785:B 2782:C 2779:S 2772:| 2750:| 2746:A 2743:B 2740:C 2733:| 2729:= 2725:| 2721:A 2718:D 2715:C 2708:| 2687:A 2684:B 2681:C 2658:A 2655:D 2652:C 2629:D 2626:B 2620:A 2617:C 2590:| 2582:| 2468:| 2464:C 2461:F 2457:| 2450:| 2446:E 2443:F 2439:| 2434:| 2430:C 2427:A 2423:| 2416:= 2412:| 2408:B 2405:A 2401:| 2379:| 2375:E 2372:F 2368:| 2359:, 2346:| 2342:A 2339:C 2335:| 2326:, 2313:| 2309:F 2306:C 2302:| 2271:m 2261:= 2254:m 2247:2 2241:m 2227:m 2214:= 2209:B 2205:A 2199:C 2193:= 2190:D 2163:m 2153:= 2148:2 2143:m 2130:+ 2126:m 2116:= 2113:C 2027:3 2024:: 2021:5 1995:B 1992:A 1963:B 1960:A 1947:m 1933:n 1930:+ 1927:m 1901:B 1898:A 1875:n 1872:: 1869:m 1843:B 1840:A 1777:1 1770:a 1749:a 1672:| 1664:| 1660:= 1645:b 1639:+ 1630:a 1616:) 1607:b 1601:+ 1592:a 1586:( 1571:= 1556:b 1536:b 1518:= 1503:a 1483:a 1439:a 1423:| 1415:| 1411:= 1399:a 1364:b 1352:+ 1343:a 1331:= 1328:) 1319:b 1313:+ 1304:a 1298:( 1211:| 1207:D 1204:F 1200:| 1193:| 1189:F 1186:B 1182:| 1175:= 1168:| 1164:C 1161:E 1157:| 1150:| 1146:E 1143:A 1139:| 1111:| 1107:D 1104:F 1100:| 1093:| 1089:C 1086:E 1082:| 1075:= 1068:| 1064:F 1061:B 1057:| 1050:| 1046:E 1043:A 1039:| 1012:E 992:S 972:F 952:F 932:E 912:S 892:S 872:S 849:S 829:C 809:A 789:S 769:S 749:S 729:S 680:| 676:D 673:C 669:| 662:| 658:C 655:S 651:| 644:= 637:| 633:B 630:A 626:| 619:| 615:A 612:S 608:| 578:| 574:D 571:B 567:| 560:| 556:C 553:A 549:| 542:= 535:| 531:D 528:S 524:| 517:| 513:C 510:S 506:| 499:= 492:| 488:B 485:S 481:| 474:| 470:A 467:S 463:| 432:| 428:D 425:S 421:| 414:| 410:C 407:S 403:| 396:= 389:| 385:B 382:S 378:| 371:| 367:A 364:S 360:| 332:| 328:D 325:C 321:| 314:| 310:D 307:S 303:| 296:= 289:| 285:B 282:A 278:| 271:| 267:B 264:S 260:| 232:| 228:D 225:C 221:| 214:| 210:C 207:S 203:| 196:= 189:| 185:B 182:A 178:| 171:| 167:A 164:S 160:| 138:. 23:.

Index

Thales's theorem
theorem
elementary geometry
line segments
rays
parallels
similar triangles
Greek mathematician
Thales
Babylonians
Egyptians
Euclid
Elements





similarity
similar triangles
conversely
vector space
axioms
scalar multiplication

compass and straightedge constructions
Trisecting the angle
Doubling the cube
Squaring the circle
field extensions

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