MathDB

440

Part of 1986 All Soviet Union Mathematical Olympiad

Problems(1)

ASU 440 All Soviet Union MO 1986 sum of angles of tetrahedron fixed

Source:

8/7/2019
Consider all the tetrahedrons AXBYAXBY, circumscribed around the sphere. Let AA and BB points be fixed. Prove that the sum of angles in the non-plane quadrangle AXBYAXBY doesn't depend on points XX and YY .
geometry3D geometryspheretetrahedronfixedanglesSum