2007 points on plane
Source: Argentina 2007 OMA L3 p6
May 12, 2024
combinatoricsgeometrycombinatorial geometry
Problem Statement
Julián chooses points of the plane between which there are no aligned, and draw with red all the segments that join two of those points. Next, Roberto draws several lines. Its objective is for each red segment to be cut inside by (at least) one of the lines. Determine the minor lines such that, no matter how Julián chooses the points, with the properly chosen lines, Roberto will achieve his objective with certainty.