4.1 Polygons - Mathematics

4.1 Polygons

4.1.1 Regular Polygons

1. A regular polygon is a polygon where

(a) all its sides are of equal length, and

(b) all its interior angles are of equal size.

2. The number of axis of symmetry of a regular polygon is equal to its number of sides.

Example:

4.1.2 Exterior and Interior Angles of Polygons

1. The exterior and interior angles at a vertex of a polygon is supplementary.

2. The sum of interior angles of an n-sided polygon is $(n - 2) \times 180^{o}$

3. Each interior angle of a regular n-sided polygon is $\frac{(n - 2) \times 180^{o}}{n}$

4. The sum of all exterior angles of a polygon is 360^o.

5. Each exterior angle of a regular n-sided polygon is

\frac{360^{o}}{n}