SQL Server/T-SQL Tutorial/Math Functions/COS

COS Returns a float value that is the cosine of the angle passed in as a parameter.

Note that this angle passed in must be in radians.
7>
8> SELECT COS(1.2)
9> GO
------------------------
     0.36235775447667362
(1 rows affected)
1> SELECT COS(ACOS(0.5))
2> GO
------------------------
     0.49999999999999989
(1 rows affected)