In the simplest form of definition, sector of a circle is a pie shaped portion of the area of the circle. It is a region bound by two radii and an arc lying between two radii.
A sector of a circle :

Area of Circle Sector: (with central angle
)
If the angle
is in degrees, then area = (
/360)x PI r2
If the angle
is in radians, then area = ((
/(2PI))x PI r2