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Axes of symmetry intersect at angle.

Source: ILL 1979-30

June 2, 2011
symmetrygeometrygeometric transformationreflectionrotationinvariantgeometry unsolved

Problem Statement

Let MM be a set of points in a plane with at least two elements. Prove that if MM has two axes of symmetry g1g_1 and g2g_2 intersecting at an angle α=qπ\alpha = q\pi, where qq is irrational, then MM must be infinite.
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