17 points out of 25 lattice points, 3 collinear whose line does not pass center
Source: 2004 Estonia National Olympiad Final Round grade 11 p 3
March 25, 2020
combinatoricscombinatorial geometry
Problem Statement
From points in a plane, both of whose coordinates are integers of the set , some points are marked. Prove that there are three points on one line, one of them is the midpoint of two others.