The input number must be between -1 and 1, inclusive.
For example, given a ratio of 0.5 the function returns the angle of 0.524 radians.
ASIN is the inverse of SIN.
ACOS Function
The ACOS function returns the inverse cosine of a number.
The function is the inverse of COS and expects input in the range from -1 to 1.
ATAN Function
The Excel ATAN function returns the inverse tangent of a number.
The function is the inverse of TAN.
