27. (5%) Let (Xi, yi), i = 1,2,3,4,5, be a set of five distinct points with integer coordinates in t
問題詳情
27. (5%) Let (Xi, yi), i = 1,2,3,4,5, be a set of five distinct points with integer coordinates in the xy plane. Showthat there is at least one of the midpoints of the segment joining of these points which has integer coordinates.