A triangle has three sides ... prism.The cross-section is a pentagon.The 3D shape is a pentagonal prism. For all polyhedra the number of edges is two less than the sum of the number of vertices ...

Pentagonal Pyramid National Museum of American History Polyhedron Model by Martin Berman, Triangular Cupola National Museum of American History Polyhedron Model by Martin Berman, Square Cupola ...

A polyhedron with eight vertices that had more ... a recreational mathematician and former mathematics teacher from Australia ...