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

X(12)
({X(1),X(5)}-HARMONIC CONJUGATE OF X(11))


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           1 + cos(B - C) : 1 + cos(C - A) : 1 + cos(A - B)
                                    = f(A,B,C) : f(B,C,A) : f(C,A,B), where f(A,B,C) = cos2(B/2 - C/2)
                                    = g(a,b,c) : g(b,c,a) : g(c,a,b), where g(a,b,c) = bc(b + c)2/(b + c - a)

Barycentrics    a(1 + cos(B - C)) : b(1 + cos(C - A)) : c(1 + cos(A - B))
                                    = h(a,b,c) : h(b,c,a) : h(c,a,b), where h(a,b,c) = (b + c)2/(b + c - a)

Let A'B'C' be the touch points of the nine-point circle with the A-, B-, C- excircles, respectively. The lines AA', BB', CC' concur in X(12).

X(12) lies on these lines:
1,5    2,56    3,498    4,55    7,1268    10,65    17,203    18,202    30,35    33,235    34,427    36,140    37,225    38,1393    40,1836    42,1834    54,215    57,1224    63,1454    71,1901    79,484    85,120    108,451    115,1500    116,1362    117,1364    121,1357    123,1359    124,1361    125,1425    141,1469    171,1399    172,230    201,756    208,1360    221,1853    228,407    281,1118    313,349    354,1210    377,1259    381,1479    431,1824    443,1466    474,1470    485,1124    486,1124    499,999    603,750    611,1352    908,960    942,1209    946,1532    968,1904    1015,1506    1038,1368    1091,1109    1125,1319    1213,1400    1452,1892    1594,1870    1697,1699    1861,1887    1877,1883

X(12) is the {X(1),X(5)}-harmonic conjugate of X(11).

X(12) = isogonal conjugate of X(60)
X(12) = isotomic conjugate of X(261)
X(12) = complement of X(2975)
X(12) = X(10)-Ceva conjugate of X(201)
X(12) = crosssum of X(58) and X(1437)
X(12) = X(I)-beth conjugate of X(J) for these (I,J): (10,12), (1089,1089)


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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