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A New Solid (Posted on 2004-10-05) Difficulty: 3 of 5
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?

See The Solution Submitted by Brian Smith    
Rating: 4.1250 (8 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re(2): Surely not the intended solution ! (spoilers) | Comment 14 of 19 |
(In reply to re: Surely not the intended solution ! (spoilers) by nikki)

I also fell for the "duh, it's 7" answer when this problem was in the queue.  I'm glad that Charlie showed me the error of my thinking (as I was not impressed by, what I thought was, the trivial nature of this problem).

It would have been a shame to have missed having this problem on the site!

  Posted by SilverKnight on 2004-10-06 03:52:53

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