1. heptagon
Wikipedia definition
2. HeptagonIn geometry, a heptagon is a polygon with seven sides and seven angles. In a regular heptagon, in which all sides and all angles are equal, the sides meet at an angle of 5π/7 radians, 128.5714286 degrees. Its Schläfli symbol is {7}. The area (A) of a regular heptagon of side length a is given by The heptagon is also occasionally referred to as the septagon, using "sept-" together with the Greek suffix "-agon" meaning angle).
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