To find the arccosine, or inverse cosine, of a number, we can use the JavaScript **acos()** function from the math module.

`Math.acos(x)`

In JavaScript, we can easily use trigonometric functions with the JavaScript math module. The JavaScript math module allows us to perform trigonometry easily.

With the JavaScript math module, we can find the arccosine of a number easily.

To find the arccosine of a number, we use the math **acos()** function.

Below is the JavaScript syntax to find the inverse cosine of a number.

`Math.acos(x)`

The input to the **acos()** function must be a numeric value between -1 and 1. The return value will be a numeric value between 0 and pi radians.

```
console.log(Math.acos(0.5))
console.log(Math.acos(0))
console.log(Math.acos(-0.75))
#Output:
1.0471975511965979
1.5707963267948966
2.4188584057763776
```

## Finding the Inverse Cosine of a Number in JavaScript

Arccosine is defined as the inverse of the cosine of a number.

Below, we show that if we pass a number to **cos()** and then call the JavaScript **acos()** function, we get back the same number.

```
console.log(Math.acos(math.cos(math.PI/3)))
console.log(Math.PI/3)
#Output:
1.0471975511965976
1.0471975511965976
```

Hopefully this article has been beneficial for you to understand how to use the math **acos()** function in Javascript to find the arccossine of a number.

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