# Math.acos( ) In JavaScript

The Math.acos( ) function in JavaScript is used to return the arccosine of a number in radians.

```Math.acos(x)=arccos(x)=unique y,
where y belongs to [0;pi]
such that cos(y)=x```

The Math.acos() method returns a numeric value between 0 and pi radians.
acos() is a static method of Math, therefore, it is always used as Math.acos(), rather than as a method of a Math object created.

Syntax:

`Math.acos(value)`

Parameters: This function accepts single parameter value which is a number in radians who arccosine you want to find.

Returns: The Math.acos() function returns the arccosine of the given number in radians.

Examples:

```Input  : Math.acos(1)
Output : 0

Input  : Math.acos(-1)
Output : 3.141592653589793

Input  : Math.acos(0)
Output : 1.5707963267948966

Input  : Math.acos(0.5)
Output : 1.0471975511965979

Input  : Math.acos(2)
Output : NaN

```
1. Example 1: When 1 is passed as a parameter.

 `<``script` `type``=``"text/javascript"``> ` `   ``document.write("Output : " + Math.acos(1)); ` ` `

Output:

`Output : 0`
2. Example 2: When -1 is passed as a parameter.

 `<``script` `type``=``"text/javascript"``> ` `   ``document.write("Output : " + Math.acos(-1)); ` ` `

Output:

`Output : 3.141592653589793`
3. Example 3: When 0 is passed as a parameter.

 `<``script` `type``=``"text/javascript"``> ` `   ``document.write("Output : " + Math.acos(0)); ` ` `

Output:

`Output : 1.5707963267948966`
4. Example 4: When 0.5 is passed as a parameter.

 `<``script` `type``=``"text/javascript"``> ` `   ``document.write("Output : " + Math.acos(0.5)); ` ` `

Output:

`Output : 1.0471975511965979`
5. Example 5: When 2 is passed as a parameter.

 `<``script` `type``=``"text/javascript"``> ` `   ``document.write("Output : " + Math.acos(2)); ` ` `

Output:

`Output : NaN`

Supported Browsers: The browsers supported by JavaScript Math.acos( ) function are listed below:

• Internet Explorer
• Firefox
• Opera
• Safari

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