Circular segment - is an area of a "cut off" circle from the rest of the circle by a secant (chord).
On the picture:
L - arc length
h - height
c - chord
R - radius
a - angle
If you know the radius and the angle, you may use the following formulas to calculate the remaining segment values:
Circular segment formulas
If you don't know the radius and the angle, you can calculate the segment parameters by the chord length and the segment height:
The formula for the segment radius by the chord and the height:
Then, you can calculate the segment angle using the following formula:
You may also use the following calculator to obtain the segment area by its radius and height:
This calculator evaluates the angle by the following formula:
then it uses formula  to calculate the segment area.
15 circular segment calculations in one program
Finally, the circular segment calculator below includes all possible calculations regarding circular segment parameters:
- arc length
- chord length
Enter two segment parameters, and the calculator will find all the rest.