120 rotations around it's center of a regular 360gon
Source: Czech-Polish-Slovak Match Junior 2019, team p5 CPSJ
January 20, 2020
geometrygeometric transformationrotationcombinatorial geometrycombinatorics
Problem Statement
Let be a regular -gon with centre . For each of the triangles and determine, whether its images under some rotations with centre can have (as triangles) all the points as vertices.