title: finding angles 0-360
body: <p>Need help with a math issue:
  i need to get the true angle from 0 degrees using x and y cordinates
  im using this at the moment:</p>
  
  <pre><code>Math.atan((x2-x1)/(y1-y2))/(Math.PI/180)
  </code></pre>
  
  <p>but <code>/(Math.PI/180)</code> limits results from -90 to 90
  i need 0-360</p>
  
  <p>note: I'm using the angle to indicate direction:</p>
  
  <ul>
  <li>0=up</li>
  <li>90=right</li>
  <li>135=45 degree right+down</li>
  <li>180=down</li>
  <li>270=left</li>
  <li>etc </li>
  </ul>