Update atn2-transact-sql.md

Text revisions to tighten and optimize the reading flow of the material. Note the rewrite of the example, to make it consistent with the definition of the ATN2 function.

Author: fbsolo

docs/t-sql/functions/atn2-transact-sql.md

@@ -42,8 +42,8 @@ ATN2 ( float_expression , float_expression )
 ```  
 
 ## Arguments  
-*float_expression*
-Is an [expression](../../t-sql/language-elements/expressions-transact-sql.md) of the **float** data type.
+*float_expression*  
+An [expression](../../t-sql/language-elements/expressions-transact-sql.md) of data type **float**.
 
 ## Return types
 **float**
@@ -53,14 +53,14 @@ The following example calculates the `ATN2` for the specified `x` and `y` compon
 
 ```sql
 DECLARE @x float = 35.175643, @y float = 129.44;  
-SELECT 'The ATN2 of the angle is: ' + CONVERT(varchar,ATN2(@x,@y ));  
+SELECT 'The ATN2 of the angle is: ' + CONVERT(varchar, ATN2(@y, @x));  
 GO  
 ```  
 
 [!INCLUDE[ssResult](../../includes/ssresult-md.md)]
 
 ```sql
-The ATN2 of the angle is: 0.265345                         
+The ATN2 of the angle is: 1.30545                         
 (1 row(s) affected)  
 ```