The COS function returns a numeric value that approximates the cosine of an angle or arc, expressed in radians, that is specified
by argument-1. The type of this function is numeric.

- Argument-1 must be class numeric.
Note: Conversion factors from degrees and Gon (grad) to radians are specified in the section Trigonometric Functions.

- The returned value is the approximation of the cosine of argument-1 and is greater than or equal to -1 and less than or equal to +1.
- Floating-point format is used for numeric non-integer results.