The formulas below describe how to find interior and exterior angles of a regular polygon with side *n*.

- sum of interior angles
** **\(= (n\ −\ 2)\ ×\ 180^\circ\) - measure of interior angle \(=\frac{n\ −\ 2}{n}\ ×\ 180^\circ\)
- sum of exterior angles \(=360^\circ\)
- measure of exterior angle \(=\frac{360^\circ}{n}\)

**Perimeter** is the distance around a shape. It can be determined by adding the lengths of all sides of the shape. **Area** is the amount of space a shape occupies. The area of an object is its length times its width and is measured in square units. For example, if a wall is 3 feet long and 2 feet wide, its area would be 6 square feet (ft^{2}).

The table below gives the formulas for the area and perimeter of basic shapes. To find the area and perimeter of a circle, use the constant *pi* (*π *= 3.14).