# @turf/polygon-tangents

# polygonTangents

Finds the tangents of a [(Multi)Polygon](http://geojson.org/geojson-spec.html#polygon) from a [Point](http://geojson.org/geojson-spec.html#point).

**Parameters**

-   `point` **[Feature](http://geojson.org/geojson-spec.html#feature-objects)<[Point](http://geojson.org/geojson-spec.html#point)>** to calculate the tangent points from
-   `polygon` **[Feature](http://geojson.org/geojson-spec.html#feature-objects)<([Polygon](http://geojson.org/geojson-spec.html#polygon) \| [MultiPolygon](http://geojson.org/geojson-spec.html#multipolygon))>** to get tangents from

**Examples**

```javascript
var polygon = turf.polygon([[[11, 0], [22, 4], [31, 0], [31, 11], [21, 15], [11, 11], [11, 0]]]);
var point = turf.point([61, 5]);

var tangents = turf.polygonTangents(point, polygon)

//addToMap
var addToMap = [tangents, point, polygon];
```

Returns **[FeatureCollection](http://geojson.org/geojson-spec.html#feature-collection-objects)<[Point](http://geojson.org/geojson-spec.html#point)>** Feature Collection containing the two tangent points

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---

This module is part of the [Turfjs project](http://turfjs.org/), an open source
module collection dedicated to geographic algorithms. It is maintained in the
[Turfjs/turf](https://github.com/Turfjs/turf) repository, where you can create
PRs and issues.

### Installation

Install this module individually:

```sh
$ npm install @turf/polygon-tangents
```

Or install the Turf module that includes it as a function:

```sh
$ npm install @turf/turf
```