Acot-func
The acot(x) function returns the inverse of the corresponding trigonometric function. x can be any value. Values returned are in the first or second quadrant. Returned values are in radians, degrees or gradians, depending upon the system.math.angularunits object property (which can also be set in the Options dialog box).
double acot(double x)
x
Returns the arccotangent of x.
acot(-1)=; //should return 2.3561944901923 acot(-10)=; //should return 3.0419240010986
asin, atan, acos, acsc