title: Find angle of a point from center of circle
body: <p>If I have an image 720, 720 that looks like this..</p>
  
  <p><img src="https://i.stack.imgur.com/npOMH.png" alt="enter image description here"></p>
  
  <p>How do I work out the angle of the touched x,y given that the center x and y are 360, 360
  A lot of calculations I see for this assume the origin is 0,0 (which is top left) so I get incorrect results.
  I am assuming 0 is always to the top and not rotated.</p>