# radians



Use the `radians` function in APL to convert an angle from degrees to radians. The conversion formula is `radians = (π / 180) × angle_in_degrees`.

`radians` is useful as a preprocessing step before calling trigonometric functions such as `sin`, `cos`, or `tan`, which all expect their input in radians. If you have angle data in degrees, pass it through `radians` before applying any trigonometric operation.

## Usage [#usage]

### Syntax [#syntax]

```kusto
radians(a)
```

### Parameters [#parameters]

| Name | Type | Required | Description                      |
| ---- | ---- | -------- | -------------------------------- |
| `a`  | real | Yes      | The angle in degrees to convert. |

### Returns [#returns]

The angle in radians corresponding to the input degree value.

## Example [#example]

Use `radians` to convert an angle in degrees to radians.

**Query**

```kusto
print result = radians(180)
```

[Run in Playground](https://play.axiom.co/axiom-play-qf1k/query?initForm=%7B%22apl%22%3A%20%22print%20result%20%3D%20radians%28180%29%22%7D)

**Output**

| result |
| ------ |
| 3.1416 |

## List of related functions [#list-of-related-functions]

* [degrees](/apl/scalar-functions/mathematical-functions/degrees): Converts radians to degrees. Use it for the inverse conversion after trigonometric computations.
* [pi](/apl/scalar-functions/mathematical-functions/pi): Returns the constant π. Use it when you want to compute radian conversions manually instead of using `radians`.
* [sin](/apl/scalar-functions/mathematical-functions/sin): Returns the sine of an angle in radians. Use `radians` to prepare degree inputs before calling `sin`.
* [cos](/apl/scalar-functions/mathematical-functions/cos): Returns the cosine of an angle in radians. Use `radians` to prepare degree inputs before calling `cos`.
* [tan](/apl/scalar-functions/mathematical-functions/tan): Returns the tangent of an angle in radians. Use `radians` to prepare degree inputs before calling `tan`.

## Other query languages [#other-query-languages]

<LanguageComparisons>
  <Accordion title="Splunk SPL users">
    Splunk SPL doesn't include a built-in `radians()` function. You compute the conversion manually by multiplying the degree value by `pi() / 180`.

    <CodeGroup>
      ```sql Splunk example
      | eval angle_rad = angle_deg * (pi() / 180)
      ```

      ```kusto APL equivalent
      ['sample-http-logs']
      | extend angle_rad = radians(angle_deg)
      ```
    </CodeGroup>
  </Accordion>

  <Accordion title="ANSI SQL users">
    In SQL Server and PostgreSQL, `RADIANS()` is a built-in function with identical semantics to the APL version.

    <CodeGroup>
      ```sql SQL example
      SELECT RADIANS(angle_deg) AS angle_rad FROM logs
      ```

      ```kusto APL equivalent
      ['sample-http-logs']
      | extend angle_rad = radians(angle_deg)
      ```
    </CodeGroup>
  </Accordion>
</LanguageComparisons>