# Python 3 - Number acos() Method

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## Description

The acos() method returns the arc cosine of x in radians.

## Syntax

Following is the syntax for acos() method −

```acos(x)
```

Note − This function is not accessible directly, so we need to import math module and then we need to call this function using math static object.

## Parameters

x − This must be a numeric value in the range -1 to 1. If x is greater than 1 then it will generate 'math domain error'.

## Return Value

This method returns arc cosine of x, in radians.

## Example

The following example shows the usage of the acos() method.

```#!/usr/bin/python3
import math

print ("acos(0.64) : ",  math.acos(0.64))
print ("acos(0) : ",  math.acos(0))
print ("acos(-1) : ",  math.acos(-1))
print ("acos(1) : ",  math.acos(1))
```

## Output

When we run the above program, it produces the following result −

```acos(0.64) :  0.876298061168
acos(0) :  1.57079632679
acos(-1) :  3.14159265359
acos(1) :  0.0
```
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