IMO 2010 Shortlist G5
Let ABCDE be a convex pentagon such that BC k AE, AB BC AE, and =ABC =CDE. Let M be the midpoint of CE, and let O be ...
Category: Geometry
Problem
Let ABCDE be a convex pentagon such that BC k AE, AB BC AE, and =ABC =CDE. Let M be the midpoint of CE, and let O be the circumcenter of triangle BCD. Given that =DMO 90, prove that 2=BDA =CDE. (Ukraine)