The wonder island
Source: Baltic Way 1994
February 21, 2006
geometrycircumcircleinradiussearchcombinatorics unsolvedcombinatorics
Problem Statement
The Wonder Island is inhabited by Hedgehogs. Each Hedgehog consists of three segments of unit length having a common endpoint, with all three angles between them . Given that all Hedgehogs are lying flat on the island and no two of them touch each other, prove that there is a finite number of Hedgehogs on Wonder Island.