Interactive Applet |
You can move the points A, B and C (click on the point and drag it).
Press the keys “+” and “−” to zoom in or zoom out the visualization window and use the arrow keys to translate it.
You can also construct all centers related with this one (as described in ETC) using the “Run Macro Tool”. To do this, click on the icon , select the center name from the list and, then, click on the vertices A, B and C successively.
Information from Kimberling's Encyclopedia of Triangle Centers |
Trilinears b + c - a : c + a - b : a + b - c
= cot(A/2) : cot(B/2) : cot(C/2)Barycentrics a(b + c - a) : b(c + a - b) : c(a + b - c)
X(9) is the symmedian point of the excentral triangle.
X(9) lies on these lines:
1,6 2,7 3,84 4,10 5,1729 8,346 21,41 31,612 32,987 33,212 34,201 35,90 38,614 39,978 42,941 43,256 46,79 48,101 55,200 56,1696 58,975 100,1005 164,168 165,910 171,1707 173,177 192,239 223,1073 228,1011 241,269 261,645 294,1253 312,314 318,1896 321,1751 342,653 348,738 364,366 374,517 393,1785 440,1211 478,1038 498,920 522,657 604,1420 607,1039 608,1041 609,1333 644,1320 654,1639 750,896 943,1802 986,1722 991,1818 1088,1223 1125,1732 1174,1621 1249,1712 1377,1703 1378,1702 1479,1752 1571,1574 1572,1573 1678,1705 1679,1704 1680,1701 1681,1700X(9) is the {X(44),X(45)}-harmonic conjugate of X(1).
X(9) = midpoint of X(I) and X(J) for these (I,J): (7,144), (8,390)
X(9) = reflection of X(I) in X(J) for these (I,J): (1,1001), (7,142)
X(9) = isogonal conjugate of X(57)
X(9) = isotomic conjugate of X(85)
X(9) = complement of X(7)
X(9) = anticomplement of X(142)
X(9) = X(I)-Ceva conjugate of X(J) for these (I,J):
(2,1), (8,200), (21,55), (63,40), (190,522), (312,78), (318,33), (329,1490), (333,8)X(9) = cevapoint of X(I) and X(J) for these (I,J): (1,165), (6,198), (31,205), (37,71), (41,212), (55,220)
X(9) = X(I)-cross conjugate of X(J) for these (I,J):
(6,282), (37,281), (41,33), (55,1), (71,219), (210,8), (212,78), (220,200)X(9) = crosspoint of X(I) and X(J) for these (I,J): (2,8), (21,333), (63,271), (312,318)
X(9) = crosssum of X(I) and X(J) for these (I,J): (6,56), (19,208), (65,1400), (244,649), (603,604), (1418,1475)
X(9) = crossdifference of any two points on line X(513)X(663)
X(9) = X(I)-Hirst inverse of X(J) for these (I,J): (1,518), (192,239)X(9) = X(I)-aleph conjugate of X(J) for these (I,J):
(1,43), (2,9), (9,170), (188,165), (190,1018), (366,1), (507,361), (508,57), (509,978)X(9) = X(I)-beth conjugate of X(J) for these (I,J):
(9,6), (190,6), (346,346), (644,9), (645,75)