title: How to efficiently find the total area of a union of circles?
body: <p>I have a data set defined as:</p>
  
  <pre><code> [
    [lat, long, radius],
    [lat, long, radius],
    ... (100-10k)
    [lat, long, radius]
   ]
  </code></pre>
  
  <p>How can I calculate the area of the reunion of all the circles?
  The sum would be the total area of all the circles - the intersection (to remove duplicate counts)?</p>