MathDB

6

Part of 1963 Polish MO Finals

Problems(1)

coplanar lines

Source: Polish MO Finals 1963 p6

8/30/2024
Through the vertex of a trihedral angle in which no edge is perpendicular to the opposite face, a straight line is drawn in the plane of each face perpendicular to the opposite edge. Prove that the three straight lines obtained lie in one plane.
geometry3D geometry