# Math.acos

## Function

Arc cosine. Returns the arccosine of value in radians.

## Syntax

```bt
Math.acos(value)
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| value | Number | Yes | None | The number involved in the calculation. |

## Return value

| Type | Description |
| ------ | ------ |
| Int/Float | Returns the arc cosine of value in radians. An Int is returned for integer results, and a Float for non-integer or non-finite results. |

## Example

```bt
result = Math.acos(1)

// Output: 0
print result
```

## Notes

- Return NaN according to the f64 rule when exceeding [-1, 1].