Choombam
Source: Iranian National Math Olympiad (Final exam) 2006
September 19, 2006
geometry3D geometryprismspheretetrahedronsymmetryperpendicular bisector
Problem Statement
A regular polyhedron is a polyhedron that is convex and all of its faces are regular polygons. We call a regular polhedron a "Choombam" iff none of its faces are triangles.
a) prove that each choombam can be inscribed in a sphere.
b) Prove that faces of each choombam are polygons of at most 3 kinds. (i.e. there is a set that each face of a choombam is -gon or -gon or -gon.)
c) Prove that there is only one choombam that its faces are pentagon and hexagon. (Soccer ball)
http://aycu08.webshots.com/image/5367/2001362702285797426_rs.jpg
d) For , a prism that its faces are 2 regular -gons and squares, is a choombam. Prove that except these choombams there are finitely many choombams.