icosidigons

An icosidigon is a polygon with 20 sides. The term is derived from Greek words meaning "twenty" and "angle". Like any polygon, an icosidigon has a number of vertices equal to its number of sides, so it also has 20 vertices. The internal angles and side lengths of an icosidigon can vary depending on whether it is equilateral and equiangular. A regular icosidigon has all sides of equal length and all interior angles equal. The sum of the interior angles of any icosidigon, regardless of its shape, can be calculated using the formula (n-2) * 180 degrees, where n is the number of sides. For an icosidigon, this sum is (20-2) * 180 = 18 * 180 = 3240 degrees. In a regular icosidigon, each interior angle measures 3240 / 20 = 162 degrees. The exterior angle of a regular icosidigon is 360 / 20 = 18 degrees. The construction of a regular icosidigon is possible with a compass and straightedge, as 20 is a product of distinct Fermat primes (5) and a power of two (4 = 2^2). Its name is sometimes used interchangeably with icosagon, though icosagon more commonly refers specifically to the 20-sided polygon.