How to find the area of a segment of a circle if we know the radius and an angle?

问题

I have some problems to find an area of a segment of a circle.

I try to use this formula but have another result, as here http://planetcalc.com/1421/ , i use calculator circle segment area to check my result from terminal.

my code:

#define PI 3.14159265

double r = 12;
double a = 22;
double result = ((r*r)/2)*(PI*(a/180)-sin(a));

回答1:

You have to correct your sin calculations a bit, it should look like this:

sin(M_PI * angle / 180)

来源：https://stackoverflow.com/questions/35807728/how-to-find-the-area-of-a-segment-of-a-circle-if-we-know-the-radius-and-an-angle