Asin-func
The asin(x) function returns the inverse of the corresponding trigonometric function. x must be within -1 and 1 for asin , or a missing value is returned. 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 asin(double x)
x
Returns the arcsine of x.
aa = asin(0.5); aa = ; //should return 0.5235987755983
acos, atan, atan2, acot, asec, acsc,