Illustration of a convex polyhedral angle. "The sum of the face angles of any convex polyhedral angle…

Diagram used to prove the theorem: "The sum of the face angles of any convex polyhedral angle is less…

Illustration of polyhedral angle. "The opening of three or more planes which meet at a common point…

Illustration used to show that two trihedral angles are equal or symmetrical when the three face angles…

Illustration of a sphere with a polyhedral angle whose vertex is at the center of the sphere and whose…