MathDB
Show that $O$;$D$;$K$ are collinear

Source: ARMO 1997, 10.6

April 20, 2013
geometry proposedgeometry

Problem Statement

A circle centered at OO and inscribed in triangle ABCABC meets sides ACAC;ABAB;BCBC at KK;MM;NN, respectively. The median BB1BB_1 of the triangle meets MNMN at DD. Show that OO;DD;KK are collinear. M. Sonkin