Circle sector area

A sector of a circle is the part of a circle bounded by an arc and two radii connecting the ends of the arc to the center of the circle. Two radii divide the circle into two sectors, and if the angle between these radii is 180 degrees, then the area of these sectors is equal.

Sector area through arc length

Sector arc length
Circle radius

Sector area through angle (in degrees)

Arc angle
Circle radius