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Area of a Segment of a Circle
Definition: The number of square units it takes to fill a segment of a circle
Try this Drag one of the orange dots that define the endpoints of the segment. Note the number of square units it takes to fill it.
(If there is no image below, see support page.)
The formula to find the area of the segment is given below. It can also be found by calculating the area of the whole pie-shaped sector and subtracting the area of the isosceles triangle △ACB.


The formula for the area of a segment of a circle is:

Central angle in degrees

where:
C  is the central angle in DEGREES
R  is the radius of the circle of which the segment is a part.
π  is Pi, approximately 3.142
sin  is the trigonometry Sine function. See Trigonometry Overview

Central angle in radians

where:
C  is the central angle in RADIANS
R  is the radius of the circle of which the segment is a part.
sin  is the trigonometry Sine function. See Trigonometry Overview

Other circle topics

General

Angles in a circle

Arcs

(C) 2009 Copyright John Page