There is a separate branch in the subject of mathematics which deals with the various kinds of shapes and figures. This branch is called Geometry. Geometry deals with 2d shapes, 3d shapes, lines, ...
Polygons can be regular or irregular in shape. A polygon is a closed 2D shape with at least three sides. A regular polygon is a polygon with all equal sides and angles. An irregular polygon is a ...
It may be useful to refer to M1 properties of angles; M1 properties of 2D shapes and M5 Polygons if necessary. The sum of the angles inside any polygon can be found by spitting the polygon into ...