## X(1142) (1ST MALFATTI-RABINOWITZ POINT)

 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.

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This applet was built with the free and multiplatform dynamic geometry software C.a.R..

 Information from Kimberling's Encyclopedia of Triangle Centers

Trilinears           f(A,B,C) : f(B,C,A) : f(C,A,B),
where f(A,B,C) = 1 - 2(1 + cos B/2)(1 + cos C/2)/(1 + cos A/2)       (M. Iliev, 5/13/07)
Trilinears           g(A,B,C) : g(B,C,A) : g(C,A,B),
where g(A,B,C) = 1 - 4 sec2(A/4)cos2(B/4)cos2(C/4)       (M. Iliev, 5/13/07)

Barycentrics    (sin A)f(A,B,C) : (sin B)f(B,C,A) : (sin C)f(C,A,B)

Let A', B', C' be the respective centers of the three Malfatti circles of ABC. Let A" be the point of intersection of lines BC' and CB', and define B" and C" cyclically. Then triangle A"B"C" is perspective to ABC, and the perspector is X(1142). (Stanley Rabinowitz, #4610, 12/29/01; coordinates by Paul Yiu, #4614, 12/30/01)

X(1142) lies on this line: 1,179

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