IMO Shortlist 1985 problem 2
Dodao/la: arhiva2. travnja 2012.
A polyhedron has
faces and is such that:
(i) all faces are isosceles triangles,
(ii) all edges have length either
(iii) at each vertex either
edges meet, and
(iv) all dihedral angles are equal.
Find the ratio
Izvor: Međunarodna matematička olimpijada, shortlist 1985