Polyhedron

Polyhedron is a solid figure bounded by plane surfaces. If its face3 are all equal and regular polygons, it is said to be a regular polyhedron, and it can be shown that only five such can exist - i.e. the tetrahedron (four faces), cube (six faces), octahedron (eight faces), dodecahedron (twelve faces), and icosahedron (twenty faces). The prism and pyramid are common examples of irregular polyhedra. A connection between the number of faces, edges, and vertices of any polyhedron is given in Euclid's theorem, which states that the sum of the number of faces and vertices is two more than the number of edges.