---
title: "ACOS (Transact-SQL) | Microsoft Docs"
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ms.date: "07/24/2017"
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f1_keywords: 
  - "ACOS"
  - "ACOS_TSQL"
dev_langs: 
  - "TSQL"
helpviewer_keywords: 
  - "cosine"
  - "ACOS function"
  - "arccosine"
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author: "edmacauley"
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---
# ACOS (Transact-SQL)
[!INCLUDE[tsql-appliesto-ss2008-all-md](../../includes/tsql-appliesto-ss2008-all-md.md)]

A mathematical function that returns the angle, in radians, whose cosine is the specified **float** expression; also called arccosine.
  
![Topic link icon](../../database-engine/configure-windows/media/topic-link.gif "Topic link icon") [Transact-SQL Syntax Conventions](../../t-sql/language-elements/transact-sql-syntax-conventions-transact-sql.md)
  
## Syntax  
  
```sql
ACOS ( float_expression )  
```  
  
## Arguments  
*float_expression*  
Is an expression of the type **float** or of a type that can be implicitly converted to **float**, with a value from -1 through 1. Values outside this range return NULL and report a domain error.
  
## Return Types  
**float**
  
## Examples  
The following example returns the ACOS of the specified number.
  
```sql
SET NOCOUNT OFF;  
DECLARE @cos float;  
SET @cos = -1.0;  
SELECT 'The ACOS of the number is: ' + CONVERT(varchar, ACOS(@cos));  
```  
  
[!INCLUDE[ssResult](../../includes/ssresult-md.md)]
  
```sql
---------------------------------   
The ACOS of the number is: 3.14159   
  
(1 row(s) affected)  
```  
  
### [!INCLUDE[ssSDWfull](../../includes/sssdwfull-md.md)] and [!INCLUDE[ssPDW](../../includes/sspdw-md.md)] 

The following example returns the ACOS of the specified number.
  
```sql
DECLARE @cos float;  
SET @cos = -1.0;  
SELECT 'The ACOS of the number is: ' + CONVERT(varchar, ACOS(@cos));  
```  
  
[!INCLUDE[ssResult](../../includes/ssresult-md.md)]
  
```sql
---------------------------------   
The ACOS of the number is: 3.14159   
  
(1 row(s) affected)  
```  
  
## See also
[Mathematical Functions (Transact-SQL)](../../t-sql/functions/mathematical-functions-transact-sql.md)  
[Functions](../../t-sql/functions/functions.md)