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Octadecagon

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A regular triangle, nonagon, and octadecagon can completely surround a point in the plane, one of 17 different combinations of regular polygons with this property. However, this pattern cannot be extended to an
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The following approximate construction is very similar to that of the enneagon, as an octadecagon can be constructed as a truncated enneagon. It is also feasible with exclusive use of compass and straightedge.
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Symmetries of a regular octadecagon. Vertices are colored by their symmetry positions. Blue mirrors are drawn through vertices, and purple mirrors are drawn through edge. Gyration orders are given in the
961:) intermediate octadecagram forms with equally spaced vertices and two edge lengths. Other truncations form double coverings: t{9/8}={18/8}=2{9/4}, t{9/4}={18/4}=2{9/2}, t{9/2}={18/2}=2{9}. 699:
of the plane: because the triangle and the nonagon both have an odd number of sides, neither of them can be completely surrounded by a ring alternating the other two kinds of polygon.
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The regular octadecagon can tessellate the plane with concave hexagonal gaps. And another tiling mixes in nonagons and octagonal gaps. The first tiling is related to a
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Straight auxiliary line g aims over the point O to the point N (virtually a ruler at the points O and N applied), between O and N, therefore no auxiliary line.
740:: {18/5} and {18/7}, using the same points, but connecting every fifth or seventh points. There are also five compounds: {18/2} is reduced to 2{9} or two 291:
Downsize the angle AMC (also 60°) with four angle bisectors and make a thirds of circular arc MON with an approximate solution between angle bisectors w
610:-1)/2 parallelograms. In particular this is true for regular polygons with evenly many sides, in which case the parallelograms are all rhombi. For the 1447:
The Lighter Side of Mathematics: Proceedings of the Eugène Strens Memorial Conference on Recreational Mathematics and its History, (1994),
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At a circumscribed circle radius r = 100,000 km, the absolute error of the 1st side would be approximately -9 mm.
579:, with sequential internal angles: 60°, 160°, 80°, 100°, and 140°. Each of the 24 pentagons can be seen as the union of an 1566: 1369: 1324: 271:
Octadecagon, an exact construction based on the angle trisection 120° by means of the tomahawk, animation 1 min 34 s.
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Cassell's Engineer's Handbook: Comprising Facts and FormulĂŚ, Principles and Practice, in All Branches of Engineering
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enumerates the number of solutions as 112018190, including up to 18-fold rotations and chiral forms in reflection.
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when reflection lines path through both edges and vertices. Cyclic symmetries in the middle column are labeled as
1513: 117: 707: 407: 383: 339: 310: 568: 1689: 1669: 1664: 1621: 1596: 703: 696: 73: 752:, {18/6} is reduced to 6{3} or 6 equilateral triangles, and finally {18/9} is reduced to 9{2} as nine 1724: 249: 1649: 1674: 1559: 1431: 1341: 2075: 2015: 1654: 1385: 1359: 1314: 1146: 720: 715: 245: 230: 1959: 1729: 1659: 1601: 1501: 1285: 1271: 749: 580: 573: 544:
Each subgroup symmetry allows one or more degrees of freedom for irregular forms. Only the
8: 2065: 2040: 2010: 2005: 1964: 1679: 1310: 261: 253: 160: 618:=9, and it can be divided into 36: 4 sets of 9 rhombs. This decomposition is based on a 2070: 1611: 525:. The dihedral symmetries are divided depending on whether they pass through vertices ( 514: 1452: 1396:(Chapter 20, Generalized Schaefli symbols, Types of symmetry of a polygon pp. 275-278) 226: 63: 2050: 1644: 1552: 1527: 1489: 1484: 1389: 1365: 1320: 958: 455: 122: 53: 305:
Thus, the circular arc MON is freely accessible for the later intersection point R.
1579: 1479: 257: 602:-gon whose opposite sides are parallel and of equal length) can be dissected into 560: 2045: 2025: 2020: 1990: 1709: 1684: 1616: 1530: 1497: 1016: 1009: 1002: 995: 986: 736:
is an 18-sided star polygon, represented by symbol {18/n}. There are two regular
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Deeper truncations of the regular enneagon and enneagrams can produce isogonal (
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labels these by a letter and group order. Full symmetry of the regular form is
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Symmetry, Shape, and Surfaces: An Introduction to Mathematics Through Geometry
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These 15 symmetries can be seen in 12 distinct symmetries on the octadecagon.
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for a number of higher-dimensional polytopes, shown in these skew
1911: 1891: 1804: 1799: 1794: 1784: 1759: 1714: 1575: 1417: 1280: 1266: 1252: 745: 595: 591: 584: 199: 1420:, Mathematical recreations and Essays, Thirteenth edition, p.141 1224: 1191: 689: 1719: 1218: 623: 1238: 1764: 753: 1213: 1202: 748:, {18/4} and {18/8} are reduced to 2{9/2} and 2{9/4} or two 632: 1399: 967:
Vertex-transitive truncations of enneagon and enneagrams
646: 462:, order 36. There are 5 subgroup dihedral symmetries: Dih 548:
subgroup has no degrees of freedom but can be seen as
411: 387: 343: 314: 410: 386: 342: 313: 1525: 1465:"Equilateral convex pentagons which tile the plane" 420: 396: 352: 323: 2088: 244:As 18 = 2 × 3, a regular octadecagon cannot be 1462: 1405: 229:{18} and can be constructed as a quasiregular 1560: 1433:The Elements of Plane Practical Geometry, Etc 1364:, American Mathematical Society, p. 31, 236:, t{9}, which alternates two types of edges. 1361:Mathematical Connections: A Capstone Course 1309: 1567: 1553: 1483: 1472:Journal of Combinatorial Theory, Series A 1083: 1033: 983: 820: 643: 567: 559: 440: 376:calculation nanogan (Berechnung, German) 266: 209: 1463:Hirschhorn, M. D.; Hunt, D. C. (1985), 1436:, John W. Parker & Son, p. 134 2089: 1429: 1357: 421:{\displaystyle \scriptstyle \angle {}} 397:{\displaystyle \scriptstyle \angle {}} 353:{\displaystyle \scriptstyle \angle {}} 324:{\displaystyle \scriptstyle \angle {}} 205: 1548: 1526: 1339: 744:, {18/3} is reduced to 3{6} or three 252:. However, it is constructible using 1574: 1388:, (2008) The Symmetries of Things, 541:for their central gyration orders. 13: 1141:A regular skew octadecagon is the 1136: 727: 626:, with 36 of 4608 faces. The list 412: 388: 344: 315: 282: 214:Octadecagon with all 135 diagonals 14: 2108: 1519: 198:) or 18-gon is an eighteen-sided 1430:Dallas, Elmslie William (1855), 1279: 1265: 1251: 1237: 1223: 1212: 1201: 1190: 1122: 1115: 1108: 1101: 1094: 1085: 1072: 1065: 1058: 1051: 1044: 1035: 1022: 1015: 1008: 1001: 994: 985: 909: 898: 889: 878: 869: 858: 847: 836: 825: 719: 714: 688: 673: 666: 659: 652: 645: 107: 102: 97: 89: 84: 79: 27: 2097:Polygons by the number of sides 1384:John H. Conway, Heidi Burgiel, 1121: 1084: 1071: 1034: 1021: 984: 888: 868: 824: 366:Example to illustrate the error 239: 1441: 1423: 1411: 1378: 1351: 1333: 1303: 1159:Octadecagonal petrie polygons 1: 1296: 821: 708:truncated trihexagonal tiling 555: 1485:10.1016/0097-3165(85)90078-0 1188: 920: 762:Compounds and star polygons 331:AMR = 19.999999994755615...° 7: 1313:; Moore, Teresa E. (2002), 521:and no symmetry is labeled 436: 10: 2113: 1406:Hirschhorn & Hunt 1985 761: 704:truncated hexagonal tiling 640:Dissection into 36 rhombs 281: 1983: 1929: 1869: 1813: 1752: 1743: 1635: 1587: 1449:Metamorphoses of polygons 1181: 1175: 1169: 1158: 974: 966: 816: 804: 533:for perpendiculars), and 360:AMR - 20° = -5.244...E-9° 174: 148: 133: 116: 72: 62: 48: 38: 26: 21: 1358:Conway, John B. (2010), 1319:, Springer, p. 86, 529:for diagonal) or edges ( 250:compass and straightedge 1346:, D. McKay, p. 528 683: 74:Coxeter–Dynkin diagrams 1147:orthogonal projections 588: 574:equilateral pentagonal 565: 564:18-gon with 144 rhombs 447: 422: 398: 354: 325: 287: 272: 215: 1386:Chaim Goodman-Strauss 1340:Adams, Henry (1907), 706:, and the second the 571: 563: 444: 423: 399: 355: 326: 286: 270: 213: 33:A regular octadecagon 16:Polygon with 18 edges 1800:Nonagon/Enneagon (9) 1730:Tangential trapezoid 1311:Kinsey, L. Christine 581:equilateral triangle 408: 384: 340: 311: 1912:Megagon (1,000,000) 1680:Isosceles trapezoid 641: 612:regular octadecagon 452:regular octadecagon 206:Regular octadecagon 22:Regular octadecagon 1882:Icositetragon (24) 1528:Weisstein, Eric W. 697:Archimedean tiling 639: 594:states that every 589: 566: 448: 418: 417: 394: 393: 350: 349: 321: 320: 288: 273: 216: 2084: 2083: 1925: 1924: 1902:Myriagon (10,000) 1887:Triacontagon (30) 1851:Heptadecagon (17) 1841:Pentadecagon (15) 1836:Tetradecagon (14) 1775:Quadrilateral (4) 1645:Antiparallelogram 1394:978-1-56881-220-5 1294: 1293: 1134: 1133: 959:vertex-transitive 955: 954: 681: 680: 434: 433: 184: 183: 2104: 1897:Chiliagon (1000) 1877:Icositrigon (23) 1856:Octadecagon (18) 1846:Hexadecagon (16) 1750: 1749: 1569: 1562: 1555: 1546: 1545: 1541: 1540: 1510: 1509: 1508: 1487: 1469: 1455: 1445: 1439: 1437: 1427: 1421: 1415: 1409: 1403: 1397: 1382: 1376: 1374: 1355: 1349: 1347: 1337: 1331: 1329: 1307: 1283: 1269: 1255: 1241: 1227: 1216: 1205: 1194: 1156: 1155: 1126: 1119: 1112: 1105: 1098: 1089: 1076: 1069: 1062: 1055: 1048: 1039: 1026: 1019: 1012: 1005: 998: 989: 980:Double covering 964: 963: 913: 902: 893: 882: 873: 862: 851: 840: 829: 759: 758: 723: 718: 692: 677: 670: 663: 656: 649: 642: 638: 635: 622:projection of a 427: 425: 424: 419: 416: 404:JMR equivalent 403: 401: 400: 395: 392: 359: 357: 356: 351: 348: 330: 328: 327: 322: 319: 279: 278: 258:angle trisection 112: 111: 110: 106: 105: 101: 100: 94: 93: 92: 88: 87: 83: 82: 31: 19: 18: 2112: 2111: 2107: 2106: 2105: 2103: 2102: 2101: 2087: 2086: 2085: 2080: 1979: 1933: 1921: 1865: 1831:Tridecagon (13) 1821:Hendecagon (11) 1809: 1745: 1739: 1710:Right trapezoid 1631: 1583: 1573: 1522: 1506: 1504: 1467: 1459: 1458: 1453:Branko GrĂźnbaum 1446: 1442: 1428: 1424: 1416: 1412: 1404: 1400: 1383: 1379: 1372: 1356: 1352: 1338: 1334: 1327: 1308: 1304: 1299: 1289: 1284: 1275: 1270: 1261: 1256: 1247: 1242: 1233: 1228: 1217: 1206: 1195: 1185: 1179: 1173: 1167: 1139: 1137:Petrie polygons 1129: 1127: 1090: 1079: 1077: 1040: 1029: 1027: 990: 979: 916: 914: 905: 903: 894: 885: 883: 874: 865: 863: 854: 852: 843: 841: 832: 830: 802:Convex polygon 730: 728:Related figures 693: 686: 627: 558: 509: 505: 501: 497: 493: 489: 481: 477: 473: 469: 465: 459: 439: 415: 409: 406: 405: 391: 385: 382: 381: 347: 341: 338: 337: 334:360° á 18 = 20° 318: 312: 309: 308: 298: 294: 242: 227:Schläfli symbol 208: 128: 108: 103: 98: 96: 95: 90: 85: 80: 78: 64:Schläfli symbol 43:Regular polygon 34: 17: 12: 11: 5: 2110: 2100: 2099: 2082: 2081: 2079: 2078: 2073: 2068: 2063: 2058: 2053: 2048: 2043: 2038: 2036:Pseudotriangle 2033: 2028: 2023: 2018: 2013: 2008: 2003: 1998: 1993: 1987: 1985: 1981: 1980: 1978: 1977: 1972: 1967: 1962: 1957: 1952: 1947: 1942: 1936: 1934: 1927: 1926: 1923: 1922: 1920: 1919: 1914: 1909: 1904: 1899: 1894: 1889: 1884: 1879: 1873: 1871: 1867: 1866: 1864: 1863: 1858: 1853: 1848: 1843: 1838: 1833: 1828: 1826:Dodecagon (12) 1823: 1817: 1815: 1811: 1810: 1808: 1807: 1802: 1797: 1792: 1787: 1782: 1777: 1772: 1767: 1762: 1756: 1754: 1747: 1741: 1740: 1738: 1737: 1732: 1727: 1722: 1717: 1712: 1707: 1702: 1697: 1692: 1687: 1682: 1677: 1672: 1667: 1662: 1657: 1652: 1647: 1641: 1639: 1637:Quadrilaterals 1633: 1632: 1630: 1629: 1624: 1619: 1614: 1609: 1604: 1599: 1593: 1591: 1585: 1584: 1572: 1571: 1564: 1557: 1549: 1543: 1542: 1521: 1520:External links 1518: 1517: 1516: 1511: 1457: 1456: 1440: 1422: 1410: 1398: 1377: 1370: 1350: 1332: 1325: 1301: 1300: 1298: 1295: 1292: 1291: 1287: 1277: 1273: 1263: 1259: 1249: 1245: 1235: 1231: 1221: 1210: 1199: 1187: 1186: 1183: 1180: 1177: 1174: 1171: 1168: 1165: 1161: 1160: 1151:Coxeter planes 1143:Petrie polygon 1138: 1135: 1132: 1131: 1120: 1113: 1106: 1099: 1092: 1091:t{9/7}={18/7} 1082: 1081: 1070: 1063: 1056: 1049: 1042: 1041:t{9/5}={18/5} 1032: 1031: 1020: 1013: 1006: 999: 992: 982: 981: 976: 973: 969: 968: 953: 952: 949: 946: 943: 940: 937: 934: 931: 928: 925: 923:Interior angle 919: 918: 907: 896: 887: 876: 867: 856: 845: 834: 823: 819: 818: 815: 812: 809: 806: 803: 800: 796: 795: 792: 789: 786: 783: 780: 777: 774: 771: 768: 764: 763: 729: 726: 725: 724: 685: 682: 679: 678: 671: 664: 657: 650: 620:Petrie polygon 557: 554: 550:directed edges 507: 503: 499: 495: 491: 487: 486:symmetries: (Z 479: 475: 471: 467: 463: 457: 438: 435: 432: 431: 430: 429: 414: 390: 378: 372: 369: 363: 362: 361: 346: 335: 332: 317: 303: 300: 296: 292: 241: 238: 207: 204: 196:octakaidecagon 182: 181: 178: 172: 171: 150: 146: 145: 142: 135:Internal angle 131: 130: 126: 120: 118:Symmetry group 114: 113: 76: 70: 69: 66: 60: 59: 56: 46: 45: 40: 36: 35: 32: 24: 23: 15: 9: 6: 4: 3: 2: 2109: 2098: 2095: 2094: 2092: 2077: 2076:Weakly simple 2074: 2072: 2069: 2067: 2064: 2062: 2059: 2057: 2054: 2052: 2049: 2047: 2044: 2042: 2039: 2037: 2034: 2032: 2029: 2027: 2024: 2022: 2019: 2017: 2016:Infinite skew 2014: 2012: 2009: 2007: 2004: 2002: 1999: 1997: 1994: 1992: 1989: 1988: 1986: 1982: 1976: 1973: 1971: 1968: 1966: 1963: 1961: 1958: 1956: 1953: 1951: 1948: 1946: 1943: 1941: 1938: 1937: 1935: 1932: 1931:Star polygons 1928: 1918: 1917:Apeirogon (∞) 1915: 1913: 1910: 1908: 1905: 1903: 1900: 1898: 1895: 1893: 1890: 1888: 1885: 1883: 1880: 1878: 1875: 1874: 1872: 1868: 1862: 1861:Icosagon (20) 1859: 1857: 1854: 1852: 1849: 1847: 1844: 1842: 1839: 1837: 1834: 1832: 1829: 1827: 1824: 1822: 1819: 1818: 1816: 1812: 1806: 1803: 1801: 1798: 1796: 1793: 1791: 1788: 1786: 1783: 1781: 1778: 1776: 1773: 1771: 1768: 1766: 1763: 1761: 1758: 1757: 1755: 1751: 1748: 1742: 1736: 1733: 1731: 1728: 1726: 1723: 1721: 1718: 1716: 1713: 1711: 1708: 1706: 1703: 1701: 1698: 1696: 1695:Parallelogram 1693: 1691: 1690:Orthodiagonal 1688: 1686: 1683: 1681: 1678: 1676: 1673: 1671: 1670:Ex-tangential 1668: 1666: 1663: 1661: 1658: 1656: 1653: 1651: 1648: 1646: 1643: 1642: 1640: 1638: 1634: 1628: 1625: 1623: 1620: 1618: 1615: 1613: 1610: 1608: 1605: 1603: 1600: 1598: 1595: 1594: 1592: 1590: 1586: 1581: 1577: 1570: 1565: 1563: 1558: 1556: 1551: 1550: 1547: 1538: 1537: 1532: 1531:"Octadecagon" 1529: 1524: 1523: 1515: 1512: 1503: 1499: 1495: 1491: 1486: 1481: 1477: 1473: 1466: 1461: 1460: 1454: 1450: 1444: 1435: 1434: 1426: 1419: 1414: 1407: 1402: 1395: 1391: 1387: 1381: 1373: 1371:9780821849798 1367: 1363: 1362: 1354: 1345: 1344: 1336: 1328: 1326:9781930190092 1322: 1318: 1317: 1312: 1306: 1302: 1290: 1282: 1278: 1276: 1268: 1264: 1262: 1254: 1250: 1248: 1240: 1236: 1234: 1226: 1222: 1220: 1215: 1211: 1209: 1204: 1200: 1198: 1193: 1189: 1163: 1162: 1157: 1154: 1152: 1148: 1144: 1128:t{9/2}={18/2} 1125: 1118: 1114: 1111: 1107: 1104: 1100: 1097: 1093: 1088: 1078:t{9/4}={18/4} 1075: 1068: 1064: 1061: 1057: 1054: 1050: 1047: 1043: 1038: 1028:t{9/8}={18/8} 1025: 1018: 1014: 1011: 1007: 1004: 1000: 997: 993: 988: 977: 972:Quasiregular 971: 970: 965: 962: 960: 950: 947: 944: 941: 938: 935: 932: 929: 926: 924: 921: 912: 908: 901: 897: 892: 881: 877: 872: 861: 857: 850: 846: 839: 835: 828: 814:Star polygon 813: 810: 808:Star polygon 807: 801: 798: 797: 793: 790: 787: 784: 781: 778: 775: 772: 769: 766: 765: 760: 757: 755: 751: 747: 743: 739: 738:star polygons 735: 722: 717: 713: 712: 711: 709: 705: 700: 698: 691: 676: 672: 669: 665: 662: 658: 655: 651: 648: 644: 637: 634: 630: 625: 621: 617: 613: 609: 605: 601: 597: 593: 586: 582: 578: 575: 570: 562: 553: 551: 547: 542: 540: 536: 532: 528: 524: 520: 516: 511: 485: 461: 453: 443: 379: 377: 374:See also the 373: 370: 367: 364: 336: 333: 307: 306: 304: 301: 290: 289: 285: 280: 277: 269: 265: 263: 259: 255: 251: 247: 237: 235: 232: 228: 224: 222: 212: 203: 201: 197: 193: 189: 179: 177: 173: 170: 166: 162: 158: 154: 151: 147: 143: 140: 136: 132: 129:), order 2×18 124: 121: 119: 115: 77: 75: 71: 67: 65: 61: 57: 55: 51: 47: 44: 41: 37: 30: 25: 20: 1870:>20 sides 1855: 1805:Decagon (10) 1790:Heptagon (7) 1780:Pentagon (5) 1770:Triangle (3) 1665:Equidiagonal 1534: 1505:, retrieved 1475: 1471: 1448: 1443: 1432: 1425: 1413: 1401: 1380: 1360: 1353: 1342: 1335: 1315: 1305: 1140: 978:Quasiregular 956: 734:octadecagram 733: 731: 701: 687: 615: 611: 607: 603: 599: 590: 545: 543: 538: 534: 530: 526: 522: 518: 512: 484:cyclic group 451: 449: 365: 274: 243: 240:Construction 219: 217: 195: 191: 185: 176:Dual polygon 2066:Star-shaped 2041:Rectilinear 2011:Equilateral 2006:Equiangular 1970:Hendecagram 1814:11–20 sides 1795:Octagon (8) 1785:Hexagon (6) 1760:Monogon (1) 1602:Equilateral 1514:octadecagon 1478:(1): 1–18, 1208:9-orthoplex 583:and an 80° 515:John Conway 474:), and (Dih 246:constructed 223:octadecagon 192:octadecagon 161:equilateral 2071:Tangential 1975:Dodecagram 1753:1–10 sides 1744:By number 1725:Tangential 1705:Right kite 1507:2020-10-30 1297:References 1197:17-simplex 991:t{9}={18} 805:Compounds 750:enneagrams 577:dissection 556:Dissection 149:Properties 68:{18}, t{9} 2051:Reinhardt 1960:Enneagram 1950:Heptagram 1940:Pentagram 1907:65537-gon 1765:Digon (2) 1735:Trapezoid 1700:Rectangle 1650:Bicentric 1612:Isosceles 1589:Triangles 1536:MathWorld 1494:1096-0899 975:isogonal 906:= 2{9/4} 866:= 2{9/2} 817:Compound 811:Compound 742:enneagons 502:), and (Z 482:), and 6 413:∠ 389:∠ 345:∠ 316:∠ 231:truncated 2091:Category 2026:Isotoxal 2021:Isogonal 1965:Decagram 1955:Octagram 1945:Hexagram 1746:of sides 1675:Harmonic 1576:Polygons 1080:=2{9/2} 1030:=2{9/4} 746:hexagons 460:symmetry 437:Symmetry 262:tomahawk 256:, or an 248:using a 234:enneagon 188:geometry 169:isotoxal 165:isogonal 123:Dihedral 54:vertices 2046:Regular 1991:Concave 1984:Classes 1892:257-gon 1715:Rhombus 1655:Crossed 1502:0787713 1418:Coxeter 917:= 9{2} 895:{18/7} 886:= 6{3} 875:{18/5} 855:= 3{6} 844:= 2{9} 833:= {18} 633:A006245 631::  596:zonogon 592:Coxeter 585:rhombus 446:center. 260:with a 221:regular 200:polygon 139:degrees 2056:Simple 2001:Cyclic 1996:Convex 1720:Square 1660:Cyclic 1622:Obtuse 1617:Kepler 1500:  1492:  1392:  1368:  1323:  1219:9-cube 1130:=2{9} 915:{18/9} 904:{18/8} 884:{18/6} 864:{18/4} 853:{18/3} 842:{18/2} 831:{18/1} 822:Image 754:digons 624:9-cube 466:, (Dih 254:neusis 225:has a 157:cyclic 153:Convex 2031:Magic 1627:Right 1607:Ideal 1597:Acute 1468:(PDF) 1149:from 936:100° 933:120° 930:140° 927:160° 799:Form 494:), (Z 470:, Dih 295:and w 190:, an 50:Edges 2061:Skew 1685:Kite 1580:List 1490:ISSN 1390:ISBN 1366:ISBN 1321:ISBN 948:20° 945:40° 942:60° 939:80° 684:Uses 629:OEIS 598:(a 2 454:has 450:The 428:AMR. 380:6.0 194:(or 180:Self 144:160° 52:and 39:Type 1480:doi 951:0° 732:An 572:An 546:g18 519:r36 510:). 506:, Z 498:, Z 490:, Z 478:Dih 456:Dih 186:In 2093:: 1533:. 1498:MR 1496:, 1488:, 1476:39 1474:, 1470:, 1451:, 1288:32 1274:31 1260:21 1246:71 1232:11 1178:10 1166:17 1153:: 794:9 756:. 710:. 614:, 552:. 523:a1 488:18 458:18 264:. 218:A 202:. 167:, 163:, 159:, 155:, 127:18 125:(D 58:18 1582:) 1578:( 1568:e 1561:t 1554:v 1539:. 1482:: 1438:. 1408:. 1375:. 1348:. 1330:. 1286:1 1272:2 1258:3 1244:1 1230:7 1184:7 1182:E 1176:D 1172:9 1170:B 1164:A 791:8 788:7 785:6 782:5 779:4 776:3 773:2 770:1 767:n 616:m 608:m 606:( 604:m 600:m 587:. 539:g 535:i 531:p 527:d 508:1 504:2 500:3 496:6 492:9 480:1 476:2 472:3 468:6 464:9 368:: 299:. 297:4 293:3 141:) 137:(

Index


Regular polygon
Edges
vertices
Schläfli symbol
Coxeter–Dynkin diagrams
Symmetry group
Dihedral
Internal angle
degrees
Convex
cyclic
equilateral
isogonal
isotoxal
Dual polygon
geometry
polygon

regular
Schläfli symbol
truncated
enneagon
constructed
compass and straightedge
neusis
angle trisection
tomahawk

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