Regular polygons

A convex polygon is said to be regular if all its sides are equal and all angles are equal.



If all the vertices of a polygon lie on a certain circle, then the polygon is called inscribed in the circle.



If all sides of a polygon are tangent to a certain circle, then the polygon is called circumscribed around the circle.
The circumscribed and inscribed circles of a regular polygon have the same center, which is called the center of the polygon. The central angle of a regular polygon is the angle at which the side from its center is visible.