# Polyhedrons!?

• Sep 5th 2010, 07:42 PM
zenith20
Polyhedrons!?
I was wondering if there's any formula to calculate the number of edges and vertices of a polyhedrons? like Dodecahedron, Icosahedrons, (or generally for polyhedrons with a certain number of faces)
• Sep 5th 2010, 08:09 PM
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Quote:

Originally Posted by zenith20
I was wondering if there's any formula to calculate the number of edges and vertices of a polyhedrons? like Dodecahedron, Icosahedrons, (or generally for polyhedrons with a certain number of faces)

The number of faces is not enough to determine the number of edges and vertices. However, we have Euler's formula

Euler's Formula

Simple example I came up with on paper to illustrate how # faces does not uniquely determine # edges and # vertices.

1) square pyramid

2) a wedge you'd use to hold a door open

Both have five faces but number of edges and vertices are different.
• Sep 5th 2010, 11:26 PM
zenith20
Thanks for your help. so we need 2 of them at least! :)