IMO 2007 Shortlist G4
Consider five points A, B, C, D, E such that ABCD is a parallelogram and BCED is a cyclic quadrilateral. Let be a line p...
Category: Geometry
Problem
Consider five points A, B, C, D, E such that ABCD is a parallelogram and BCED is
a cyclic quadrilateral. Let be a line passing through A, and let intersect segment DC and
line BC at points F and G, respectively. Suppose that EF = EG = EC. Prove that ` is the
bisector of angle DAB.
(Luxembourg)