Estonian Math Competitions 2005/2006
Source: Juniors Problem 2
July 30, 2008
geometryparallelogramangle bisectorgeometry unsolved
Problem Statement
Let ABCD be a parallelogram, M the midpoint of AB and N the intersection of CD
and the angle bisector of ABC. Prove that CM and BN are perpendicular iff AN is the angle bisector of DAB.