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