title: How to calculate distance between 2 points (Lambert EU projection coordinates)
body: <p>I'm a real noob when it comes to coordinate systems/projections and calculations, so please speak to me as a dummy :) </p>
  
  <p>I have coordinate data (it's written that this is Lambert EU projection), which looks as follows: </p>
  
  <pre><code>R A00   x_center    y_center
  1 svk   519922,4822 2089546,836
  2 aut   486321,4714 2087458,014
  3 aut   493858,9945 2085882,625
  </code></pre>
  
  <p>Now my first trouble is, I can find a whole bunch of calculations and formulas dealing with WGS84 coordinates, but I've never seen such coordinates as above.</p>
  
  <p>The target is:</p>
  
  <ul>
  <li>I would need to calculate the distance in km between two points, for example row 1 (x, y) and row 2 (x, y).</li>
  <li>I would need the easiest formula available (high precision is not required)</li>
  <li>The calculation should then be done in Oracle PL/SQL (PL/SQL code as your answer is nice to have but not required, I'm more concerned with the given coordinates and how to calculate distance in kilometers with them).</li>
  </ul>
  
  <p>Can someone point me to the right direction? Thanks</p>