MathDB
Area Smaller, Smaller...

Source: 1992 National High School Mathematics League, Exam Two, Problem 3

February 27, 2020
geometry

Problem Statement

In coordinate system, there are six points Pi(xi,yi)(i=1,2,,6)P_i(x_i,y_i)(i=1,2,\cdots,6), satisfying: (1) xi,yi{2,1,0,1,2}x_i,y_i\in\{-2,-1,0,1,2\}. (2) For any three points, they are not collinear. Prove that there exists a triangle PiPjPk(1i<j<k6)\triangle P_iP_jP_k(1\leq i<j<k\leq6), its area is not larger than 22.