cos - Returns the cosine for the value in C

 #include <math.h>
  #include <stdio.h>
  int main(void)
  {
  double val = -0.7;
  printf("Cosine of %f is %f.\n", val, cos(val));
  return 0;
  }


Output:
Cosine of -0.700000 is 0.764842.