A heptagon is defined as polygon with seven angles and seven sides. The heptagon is sometimes referred to as the septagon, using the Latin numerical prefix "sept" rather than the Greek numerical prefix "hepta."
In a regular heptagon, one in which all sides and angles are equal to each other, each interior angle is equal to approximately 128.57 degrees, with the sum of all interior angles being equal to 900 degrees. The area of a regular heptagon can be found by multiplying 3.63 by the length of one side squared. Though heptagonal features are rarely found in nature and are uncommon in man-made objects, the United Kingdom famously uses a heptagonal coin as its 50 pence piece.