MathDB
Two lines separating plane

Source: Korea National 2013 #8

November 10, 2013
combinatoricsKorea

Problem Statement

For positive integer a,b,c,da,b,c,d there are a+b+c+da+b+c+d points on plane which none of three are collinear. Prove there exist two lines l1,l2l_1, l_2 such that (1) l1,l2l_1, l_2 are not parallel. (2) l1,l2l_1, l_2 do not pass through any of a+b+c+da+b+c+d points. (3) There are a,b,c,d a, b, c, d points on each region separated by two lines l1,l2l_1, l_2 .
Back to ProblemsView on AoPS