title: Find center of a circle
body: <p>I need some c# code for the following:</p>
  
  <p>I have two points (2D). The points are on a circle with radius r. I know the tangent angle in each of the points. I need to get hold of the circle mid point.</p>
  
  <p>//Thomas</p>
  
  <hr>
  
  <p>OK, I think I was a bit unclear. See image below. The point P1 is at the end of a line, the line has the angle At1. The point P2 is at the beginning of a line with the angle At2. I know the coordinates for P1 and P2. I also know the angles At1 and At2. A radius is formed between P1 and P2 and I need to know the center point Pc for the (invisible) circle the which is formed with P1, P2, At1 and At2. The points P1 and P2 can be anywhere in the coordiante system.</p>
  
  <p>I know it's not c#, however I was hoping to come across someone who's solved this.</p>
  
  <p><a href="http://thomashellstrom.com/centerpoint.png" rel="nofollow">See image</a></p>