Polygon with colorful isosceles triangles
Source: Kvant Magazine No. 2 2020 M2593
March 10, 2023
combinatoricsColoringKvant
Problem Statement
Each vertex of a regular polygon is colored in one of three colors so that an odd number of vertices are colored in each of the three colors. Prove that the number of isosceles triangles whose vertices are colored in three different colors is odd.From foreign Olympiads