C库函数 sin()

#include <stdio.h>

#include <math.h>



#define PI 3.14159265



int main () {

   double x, ret, val;

   x = 45.0;

   val = PI / 180;

   ret = sin(x*val);

   printf("The sine of %lf is %lf degrees", x, ret);



   return(0);

}