en.wikipedia.org/wiki/Arc_(geometry)

To get the area of the arc segment, we need to subtract the area of the triangle,
determined by the circle's center and the two ...

www.purplemath.com/modules/sectors.htm

Explains formulas for areas of sectors of circles and lengths of arcs.
Demonstrates how to use the formulas in each of degrees and radians.

www.coolmath.com/reference/circles-trigonometry

Definitions and formulas for the arc and the arc length of a circle, sector and the
area of the sector of a circle, the unit circle, the angles on the unit circle in ...

www.coolmath.com/reference/circles-geometry

Definitions and formulas for the radius of a circle, the diameter of a circle, the
circumference (perimeter) of a circle, the area of a circle, the chord of a circle, arc
...

www.mathsisfun.com/geometry/circle-sector-segment.html

And the Segment, which is cut from the circle by a "chord" (a line between two ...
You can work out the Area of a Sector by comparing its angle to the angle of a ...

www.mathopenref.com/arcsectorarea.html

The formula used to find the area of a circlular sector - a pie-shaped part of a ...
Area. = R. L. 2. where: L is the arc length. R is the radius of the circle of which the
...

www.mathopenref.com/arclength.html

Definition of arc length and formula to calculate it from the radius and central
angle of the arc.

mathworld.wolfram.com/CircularSegment.html

of the (shaded) segment is then simply given by the area of the circular sector (
the entire wedge-shaped ... so the geometric centroid of the circular segment is ...

www.regentsprep.org/regents/math/geometry/gp16/circlesectors.htm

www.khanacademy.org/math/geometry/hs-geo-circles/hs-geo-sectors/v/area-of-a-sector-given-a-central-angle

A worked example of finding the area of a circle's sector using the area of the
circle ... Some of the geometry section overlaps with the trigonometry section,
which ... If you know the arc length and the radius, then the angle that is
subtended by ...