IMO 2007 Shortlist C8
Given a convex n-gon P in the plane. For every three vertices of P, consider the triangle determined by them. Call such ...
Category: Combinatorics
Problem
Given a convex n-gon P in the plane. For every three vertices of P, consider the triangle determined by them. Call such a triangle good if all its sides are of unit length. Prove that there are not more than 2 n good triangles. (Ukraine)