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 Used:
Value:A number in radians who arccosine you want to find.

Return Value:
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. When 1 is passed as a parameter.

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

   Output:

   Output : 0

2. When -1 is passed as a parameter.

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

   Output:

   Output : 3.141592653589793

3. When 0 is passed as a parameter.

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

   Output:

   Output : 1.5707963267948966

4. When 0.5 is passed as a parameter.

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

   Output:

   Output : 1.0471975511965979

5. When 2 is passed as a parameter.

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

   Output:

   Output : NaN