among 6 lines in space here are 3 mutually oblique lines
Source: Polish MO Second Round 1971 p3
September 8, 2024
geometrycombinatoricscombinatorial geometry3D geometrylines
Problem Statement
There are 6 lines in space, of which no 3 are parallel, no 3 pass through the same point, and no 3 are contained in the same plane. Prove that among these 6 lines there are 3 mutually oblique lines.