Gold and Black Vertices - [Canadian Repêchage 2011]
Source:
January 15, 2011
functiongeometrycongruent trianglescombinatorics proposedcombinatorics
Problem Statement
Each vertex of a regular -gon is colored black or gold. All possible triangles are formed using these vertices. Prove that there are either two congruent triangles with three black vertices or two congruent triangles with three gold vertices.