Rings containing integer points
Source: 2022 Israel TST 8 P2
May 21, 2022
number theorygeometry
Problem Statement
Define a ring in the plane to be the set of points at a distance of at least and at most from a specific point , where are positive real numbers. Rings are determined by the three parameters . The area of a ring is labeled . A point in the plane for which both its coordinates are integers is called an integer point.a) For each positive integer , show that there exists a ring not containing any integer point, for which and .b) Show that each ring satisfying contains an integer point.