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 Amazing coincidence by Ken Haley)

Geo Mags!  I love those things.  I spent a whole hour or so in FAO Schwartz playing with those once.  I highly recommend them =)

Posted by nikki on 2004-10-06 08:12:03