A regular nonagon and four equilateral triangles. The purple and yellow triangles share a vertex. Prove that the yellow triangles also share a vertex.

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geometry puzzles

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- Post author By Rik D. Tangerman
- Post date September 12, 2023
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- Post author By Rik D. Tangerman
- Post date August 30, 2023
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A regular nonagon and two equilateral triangles. What’s the angle α?