Include: Prototype: double cos(double x); double sin(double x); double tan(double x); Returns: (cos) the cosine of x if successful, or 0 if not (sin) the sine of x if successful, or 0 if not (tan) the tangent of x if successful, or 0 if not See also: acos, asin, atan, atan2, matherr, sinh, tanh The acos, asin, atan, and atan2 functions return the arccosine, the arcsine and the arctangent values of x respectively. The argument x is specified in radians. The atan2 function uses the signs of both arguments to determine the quadrant of the return value. The functions, argument range and return value range are listed below: Function Argument Range Return Value Range acos -1 to 1 0 to ã asin -1 to 1 -ã/2 to ã/2 atan no limit -ã/2 to ã/2 atan2 no limit -ã to ã Return Value The return values for these functions are described above. For the acos and asin functions, x must be between -1 and 1. If x is less than -1 or greater than 1, acos and asin set errno to EDOM, print a DOMAIN error message to stderr, and return 0. If both arguments to atan2 are 0, the function sets errno to EDOM, prints a DOMAIN error message to stderr, and returns 0. Error handling can be modified with the matherr routine. The cos, sin, and tan trigonometric functions return the cosine, sine and tangent respectively, of x. Return Value If x is large, a partial loss of significance in the result may occur in a trigonometric function, in which case the function generates a PLOSS error. If x is so large that significance is completely lost, the function prints a TLOSS message to stderr and returns 0. In both cases, errno is set to ERANGE.