A sphere is inscribed into a quadrangular pyramid
Source: I.F.Sharygin contest 2009 - Correspondence round - Problem 24
May 31, 2009
geometry3D geometryspherepyramidgeometry proposed
Problem Statement
A sphere is inscribed into a quadrangular pyramid. The point of contact of the sphere with the base of the pyramid is projected to the edges of the base. Prove that these projections are concyclic.