MathDB
2 parallelograms on consecutive sides of ABCD

Source: IGO Elementary 2016 3

July 22, 2018
geometryparallelogram

Problem Statement

Suppose that ABCDABCD is a convex quadrilateral with no parallel sides. Make a parallelogram on each two consecutive sides. Show that among these 44 new points, there is only one point inside the quadrilateral ABCDABCD.
by Morteza Saghafian