A regular tetrahedron has four equilateral triangles as faces. A regular square pyramid has four equilateral triangles and a square as faces. The faces of the tetrahedron are congruent to the triangular faces of the square pyramid.

A new polyhedron is created by gluing the tetrahedron and the square pyramid together at a triangular face so that the vertices of the triangles coincide. How many faces does this polyhedron have?

(In reply to by )

It's an oblique triangular prism.  I don't know if there's a more specific name for the particular degree of obliqueness and the fact that the ends are equilateral triangles.

Posted by Charlie on 2004-10-05 20:25:48