2009 ToT Spring Junior O P1 diagonals in a convex 2009-gon
Source:
March 7, 2020
convex polygonconvexdiagonalcombinatorial geometryEvengeometry
Problem Statement
In a convex -gon, all diagonals are drawn. A line intersects the -gon but does not pass through any of its vertices. Prove that the line intersects an even number of diagonals.