Problem 496. Triangle, Two Squares, 90 Degrees, Concurrency.
Level: High School, College, SAT Prep.
The figure shows a triangle ABC with the squares ABDE and BCFG. AG
and CD meet at P. Prove that: (1) CD and AG are congruent and
perpendicular. (2) CD, AG, and EF are concurrent at P. (3) EF is
the angle bisector of angle GPC.