heptagon
A heptagon is a polygon with seven vertices and seven sides.
There are two types of heptagon:
Regular heptagons and irregular heptagons have seven sides, and the interior angles of both add up to a total of 900°. The interior angles of a regular heptagon are always 128.57° to two decimal places, 900° ÷ 7 = 128.57°. The interior angles of an irregular heptagon are not all equal.