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 re: Amazing coincidence by nikki)

Geo mags--Is that what they're called?  Now I can find a set for myself.  They're great fun.

Thanks, nikki.  

Posted by Ken Haley on 2004-10-08 00:09:30