acos function
Applies to: 
Databricks SQL Databricks Runtime
Returns the inverse cosine (arccosine) of expr.
Syntax
acos(expr)
Arguments
expr: A numeric expression.
Returns
A DOUBLE.
If the argument is out of bounds, NaN is returned.
Examples
SQL
> SELECT acos(1);
0.0
> SELECT acos(2);
NaN