2002 OIM Problems/Problem 2
Problem
Given any set of 9 points in the plane of which there are not three collinear, show that for each point of the set, the number of triangles that have as vertices to three of the remaining eight points and to inside it, it is even.
~translated into English by Tomas Diaz. ~orders@tomasdiaz.com
Solution
This problem needs a solution. If you have a solution for it, please help us out by adding it.