MathDB
ASU 121 All Soviet Union MO 1969 n points in space angle > 120

Source:

June 23, 2019
geometrycombinatorial geometrypoints in space

Problem Statement

Given nn points in the three dimensional space such, that the arbitrary triangle with the vertices in three of those points contains an angle greater than 120120 degrees. Prove that you can rearrange them to make a polyline (unclosed) with all the angles between the sequent links greater than 120120 degrees.