MathDB
2020 PUMaC Team 11

Source:

January 1, 2022
combinatoricscombinatorial geometrygeometry

Problem Statement

Three (not necessarily distinct) points in the plane which have integer coordinates between 1 1 and 20202020, inclusive, are chosen uniformly at random. The probability that the area of the triangle with these three vertices is an integer is a/ba/b in lowest terms. If the three points are collinear, the area of the degenerate triangle is 00. Find a+ba + b.