For example, the cosine of PI()/6 radians (30) returns the ratio 0.866.
Geometrically, the function returns thex-component of the point corresponding to an angle on the unit circle.
TAN Function
The Excel TAN function returns the tangent of the angle given in radians.
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.
