**2.1 Polygons II**

**2.1.1 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:Example:

**2.1.2 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

**$\left(n-2\right)\times {180}^{o}$**

3.

3.

**Each interior angle**of a

**regular**polygon is

*n*-sided**$\frac{\left(n-2\right)\times {180}^{o}}{n}$**

**The**

4.

4.

**sum**of

**all exterior angles**of a polygon is

**360**.

^{o}

**5.**Each exterior angle of a regular

*n*-sided polygon is $\frac{{360}^{o}}{n}$