asin Arc sine &reftitle.description; floatasin floatnum Returns the arc sine of num in radians. asin is the inverse function of sin, which means that a==sin(asin(a)) for every value of a that is within asin's range. &reftitle.parameters; num The argument to process &reftitle.returnvalues; The arc sine of num in radians &reftitle.seealso; sin asinh acos atan