# Circular Sector

## Circular Sector

Portion of a circle enclosed between two radii.

### Formulas

• To calculate the area A in degrees: A = $$\dfrac{α}{360}$$ × πr$$^{2}$$
• To calculate the area A in radians: A = $$\dfrac{αr^{2}}{2}$$

### Examples

For a sector whose angle α is 90° (or π2 in radians) and whose radius r measures 10 cm, we have:

• In degrees: $$A = \dfrac{a}{360} × π r^{2}= \dfrac{90}{360} × 100π = 25π$$.
• In radians: $$A = \dfrac{αr^{2}}{2} = \dfrac{\dfrac{π}{2} × 10^{2}}{2} = 25π$$.