title: Expanding a radius around a polygon of lat/long for X miles
body: <p>I'm working on a project which requires me to build a function to expand a polygon of long/lat in a distance of X miles to create a &quot;border&quot;.</p>
  <p><img src="https://i.stack.imgur.com/BYz9O.png" alt="Example of border around a polygon to X number of miles" /></p>
  <p>The technology i am using is JavaScript deskgl / nebula gl layers. And i am unsure whether javascript deskgl/nebula gl has the built in ability to perform these operations. If not, this leads me to question the maths behind this functionality.</p>
  <p>As i am unfamiliar with long an lat on a 2d plane, nor whether the stack i am using can deal with this, how do i go about expanding an array of arrays (long, lat) by X number of miles.</p>