The acsc(x) function returns the inverse of the corresponding trigonometric function csc(x)=1/sin(x). Absolute value of x must greater than or equal to 1 for acsc, or a missing value is returned. Values returned are in the first or fourth quadrant. Returned values are in the units are determined by the system.math.angularunits object property (which can also be set in the Options dialog box).
double acsc(double x)
Returns the arccosecant of x.
acsc(5)=; //should return 0.20135792079033
Asin, Acos, Asec, Atan,