INSTITUTO DE MATEMÁTICA
HJB --- GMA --- UFF

X(9)
(MITTENPUNKT)


Click here to access the list of all triangle centers.

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 Run Macro Tool, select the center name from the list and, then, click on the vertices A, B and C successively.

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Download all construction files and macros: tc.zip (10.1 Mb).
This applet was built with the free and multiplatform dynamic geometry software C.a.R..


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    1681,1700

X(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)


This is a joint work of
Humberto José Bortolossi, Lis Ingrid Roque Lopes Custódio and Suely Machado Meireles Dias.

If you have questions or suggestions, please, contact us using the e-mail presented here.

Departamento de Matemática Aplicada -- Instituto de Matemática -- Universidade Federal Fluminense




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