Prove that APRQ is a parallegoram
Source:
September 9, 2010
trigonometrygeometryparallelogramTriangleIMO Shortlist
Problem Statement
On the sides of the triangle , three similar isosceles triangles , , and are constructed. The first two are constructed externally to the triangle , but the third is placed in the same half-plane determined by the line as the triangle . Prove that is a parallelogram.