Returns the arc cosine (in radians) of a specified number. The arc cosine is the angle whose cosine is the specified number.
[Visual Basic] Public Shared Function Acos( _ ByVal d As Double _ ) As Double [C#] public static double Acos( double d ); [C++] public: static double Acos( double d ); [JScript] public static function Acos( d : double ) : double;
Returns an angle q, measured in radians, such that 0 q . Returns NaN if d <-1 or d > 1.
To convert the result from radians to degrees, multiply it by 180/.