Tangent points of a quadrilateral to a sphere are coplanar
Source: Spanish Mathematical Olympiad, National Stage, 2011
August 9, 2011
geometry3D geometryspheregeometry unsolved
Problem Statement
Let , , , be four points in space not all lying on the same plane. The segments , , , and are tangent to the same sphere. Prove that their four points of tangency are coplanar.