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# Triangles and regular 13-sided polygon.

Problem is this: A regular 13-sided polygon is inscribed in a circle with centre O. Triangles can be formed by joining three vertices of this polygon. How many of the triangles that can be formed in this way will contain the point O in their interior?

Any easy and simple solutions will be welcomed !!! :)

Note by Alexander Freeman
3 years, 11 months ago

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