MathDB
dividing square in different no of sides convex polygons, at least 1 is triangle

Source: 2012 Sharygin Geometry Olympiad Final Round 8.8

August 3, 2018
geometryconvex polygonsquare

Problem Statement

A square is divided into several (greater than one) convex polygons with mutually different numbers of sides. Prove that one of these polygons is a triangle.
(A.Zaslavsky)