



 
Fnavroth, It is easy to compute the inradius of an icosahedron, but it is even easier to look it up. I use the appendix of Coxeter's REGULAR POLYTOPES, but you can find it on the web: http://en.wikipedia.org/wiki/Icosahedron Of course, you also need the formula for the area of an equilateral triangle and for the volume of a sphere. Chris  


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