NARRATOR: It's crunch time for the 3D crew. And who's going ... For example a cube has 12 edges, a cylinder has two and a sphere has none. Vertices - A vertex is a corner where edges meet.

Image caption, 3D shapes that are non-polyhedral include cylinders, cones ... Three square faces meet at a vertex. A prism has two end faces that match the cross-section, plus a rectangular ...