

Geometry Problem 577: Isosceles triangle, Midpoint, Perpendicular, Concyclic points, Circle. Level: Math Education, High School, College

The figure shows an isosceles triangle ABC
(AB = BC). D is the midpoint of AC and DE is perpendicular to BC. F is
the midpoint of DE and AE intersects BF at G. Prove that the points A, D,
G, and B are concyclic (lie on a same circle).







