acos function returns the cosine value(=radian) of the argument.
double @acos(double d);
Arguments
double d : number ( -1 <= d <= 1 )
Return Value
radian ( 0 ¡Â ¥è ¡Â ¥ð )
Sample
value = @acos(0.5);
Description : The cosine value of '0.5' is stored in the variable named 'value'.
Reference