#include <cmath>
    double asin( double arg );

The asin() function returns the arc sine of arg, which will be in the range [- pi/2, +pi/2]. arg should be between -1 and 1. If arg is outside this range, asin() returns NAN and raises a floating-point exception.

C++ also provides the following overloaded forms:

    #include <cmath>
    float asin( float arg ); // same as asinf() in C99
    long double asin( long double arg ); // same as asinl() in C99

Related Topics: acos, atan, atan2, cos, cosh, sin, sinh, tan, tanh