In a triangle ABC, the cevians AA_{1},
BB_{1}, and CC_{1} are concurrent at D (see figure below).
The circumcircle of the triangle A_{1}B_{1}C_{1}
cuts BC, AC, and AB at A_{2}, B_{2}, and C_{2},
respectively. Prove that the cevians AA_{2}, BB_{2},
and CC_{2} are concurrent.
Geometry Problem 1233 in Motion
Click on the figure below.
