2.1 Polygons II


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:


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  ( n 2 ) × 180 o  

3. 
Each interior angle of a regular n-sided polygon is
( n 2 ) × 180 o n

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

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