What is polygon 20 sides?

A polygon with 20 sides is called an icosagon. The sum of all interior angles of an icosagon is 3240 degrees. An icosagon can be inscribed in a circle and its exterior angles are 18 degrees each. It has 30 diagonals, which are line segments connecting any two non-adjacent vertices of the polygon. The formula for finding the number of diagonals in an n-sided polygon is n(n-3)/2, so for a 20-sided polygon, the number of diagonals is (20 x 17)/2 = 170. The regular icosagon has all sides and angles equal and the same symmetry as a regular hexagon.