# atan()

Published Jul 24, 2023
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The built-in math function `atan()` determines the arc tangent of a given value. It is also known as the inverse tangent function, it identifies the angle whose tangent is equal to the specified value. The inverse function of `atan()` is the `tan()` function.

## Syntax

``````\$result = atan(\$number);
``````

The `atan()` function takes one parameter:

• `\$number` (required): The number for which the arc tangent is to be calculated.

The `atan()` method returns a floating point number which is the arc tangent value of the number passed. The resulting numeric value will be between -pi/2 and pi/2 radians.

To convert radians to degrees, use the following:

``````\$degrees = \$radians * ( 180.0 / M_PI );
``````

## Example

The example below illustrates the use of the `atan()` function to calculate the arc tangent of a number and print the result.

```<?phpecho("atan(0.5): " . atan(0.5) . " Radians");?>
```

This will result in the following output:

```atan(0.5): 0.46364760900081 Radians
```

## Codebyte Example

The example below uses the `atan()` function to obtain the arc tangent value of a number in radians, and then converts it into degrees.

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