Nice, maybe easy, geocombi.
Source: Mexico 1995 National Olympiad Problem 2
July 24, 2014
geometrycircumcirclecombinatorics unsolvedcombinatorics
Problem Statement
Consider 6 points on a plane such that 8 of the distances between them are equal to 1. Prove that there are at least 3 points that form an equilateral triangle.