Gonian

Gonian is a term used in geometry to describe a polygon with seven sides and seven angles. The prefix "goni-" comes from the Greek word "gonia," which means "angle." Therefore, a gonian is also known as a heptagon. The internal angles of a regular gonian sum up to 900 degrees, and each internal angle of a regular gonian measures 128.57 degrees. The area of a regular gonian can be calculated using the formula (7/4) * a^2 * cot(π/7), where "a" is the length of a side. Gonian is a type of polygon that is less common in everyday use but is an important concept in geometry and mathematics.