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A triangle T is contained inside a point-symmetrical polygon

Source: Russian Olympiad 2004, problem 10.7

May 3, 2004
geometrygeometric transformationreflectionsymmetryhomothetyparallelogramgeometry solved

Problem Statement

A triangle T T is contained inside a point-symmetrical polygon M. M. The triangle T T' is the mirror image of the triangle T T with the reflection at one point P P, which inside the triangle T T lies. Prove that at least one of the vertices of the triangle T T' lies in inside or on the boundary of the polygon M. M.