Stuck in a big rut - need a math major [SOLVED] [SOLVED] hlp plz need a math major I just thought of this and I can't find a shape that matches this description: Are there any 3D shapes with only faces that have coplanar matches with other faces in the shape? It's really off-topic, I know, but I've tried to sketch something out to no avail. Is there something I'm missing? Is there already an established rule/theorem to cover this case? I'm pretty clueless :O lastly, why is this bugging me so much? Edit: When I say "coplanar faces", I mean faces that can have a ruler lay flat across them. So, not parallel or intersecting. Each face must have at least one coplanar match. I didn't want to bring this problem to a place like http://math.stackexchange.com/ because it might be an obvious, well-established rule that I don't know and aaaahhhhhhhh Edit edit: Got convinced that I should post in on stackexchage, so here's the other post if you would like to see for whatever reason.