RU-ALLRUSSIAN 1961 Problem 1
Given 12 vertices and 16 edges arranged as follows:
Draw any curve which does not pass through any vertex. Prove that the curve cannot intersect each edge just once. Intersection means that the curve crosses the edge from one side to the other. For example, a circle which had one of the edges as tangent would not intersect that edge.
Dataset text NuminaMath olympiads. Quoted with source.
Solutions
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