My friend finished making dodecahedrons, and her next project is to make regular icosahedrons (20-sided dice). Again she wants to know: what is the dihedral angle between any two adjacent faces?

Perhaps this can be solved without the use of spherical trig? ;P

(In reply to solution by Tim Axoy)

Did I really do this solution?

Posted by Tim Axoy on 2003-06-09 10:19:41