ACOS Returns as a float data type, the angle in radians that corresponds to the entered cosine, which must have values between -1 and 1. : ACOS « Math Functions « SQL Server / T-SQL Tutorial

1. SQL Server / T-SQL Tutorial
2. Math Functions
3. ACOS

This function is the inverse of COS.

6>
7> SELECT ACOS(0.33)
8> GO

------------------------
      1.2344927516409163

(1 rows affected)