acos() - math.h

The C library function double acos(double x) returns the arc cosine of x in radians.

Syntax

double acos(double x)

Example

#include <stdio.h>
#include <math.h>

#define PI 3.14159265

int main ()
{
   double x, ret, val;

   x = 0.9;
   val = 180.0 / PI;

   ret = acos(x) * val;
   printf("The arc cosine of %lf is %lf degrees", x, ret);
   
   return(0);
}

Output / Return Value

The arc cosine of 0.900000 is 25.855040 degrees

Limitations

Alternatives / See Also

Reference