Find the area of a Sector external image master6.gif

Again we'll use a circle with radius 15 cm and central angle 60°.

The first step once again is to find out what fraction of the circle
is represented by the central angle 60°:
external image calc0.gif
The sector represents 1/6 of the circle,
or 0.1666... of the circle.

To find the sector area A, we now need to find the area of the full circle, and then find 1/6 of it (multiply it by 0.1666...)
external image calc03.gif external image calc04.gif
This is the area of the sector, A.
This method will work for any sector in any circle. You just need to find the fraction of the circle that the sector angle represents, and then find that fraction of the area.