MathDB
1993 points in each quadrant of the circle

Source: IMO Shortlist 1993, Brasil 1

March 14, 2006
algebrageometrypoint setdistancecombinatorial geometryIMO Shortlist

Problem Statement

Show that there exists a finite set AR2A \subset \mathbb{R}^2 such that for every XAX \in A there are points Y1,Y2,,Y1993Y_1, Y_2, \ldots, Y_{1993} in AA such that the distance between XX and YiY_i is equal to 1, for every i.i.