ASU 413 All Soviet Union MO 1985 7 of 24 triangles in a hexagon
Source:
August 5, 2019
combinatoricscombinatorial geometryhexagon
Problem Statement
Given right hexagon. The lines parallel to all the sides are drawn from all the vertices and midpoints of the sides (consider only the interior, with respect to the hexagon, parts of those lines). Thus the hexagon is divided onto triangles, and the figure has nodes. different numbers are written in those nodes. Prove that at least of triangles have the property: the numbers in its vertices increase (from the least to the greatest) counterclockwise.