ASU 448 All Soviet Union MO 1987 3 closed broken lines in plane, odd edges
Source:
August 7, 2019
geometrycombinatoricscombinatorial geometryoddconvexbroken line
Problem Statement
Given two closed broken lines in the plane with odd numbers of edges. All the lines, containing those edges are different, and not a triple of them intersects in one point. Prove that it is possible to chose one edge from each line such, that the chosen edges will be the opposite sides of a convex quadrangle.