title: Calculate SVG path arc parameters
body: <p>How exactly can one calculate all required parameters for SVG path arc? Is there a source with a set of formulas somewhere available? A compendium without all the geometry background and without lengthly explanations?</p>
  <p>I have been fiddeling with an online tool <a href="http://xahlee.info/js/svg_circle_arc.html" rel="nofollow noreferrer">http://xahlee.info/js/svg_circle_arc.html</a> but the resulting parameters seem to be all intervowen in some way.</p>
  <p>For my specific application to draw an arc that has an appearence similar to the letter 'C', I exactly have four givens: The coordinates for the two ends of the arc, the height and the leftmost point:</p>
  <pre><code>Height: 29.0
  Leftmost point: x=0 y=(29/2)=14.5
  Upper end of the arc: x1=20 y1=6
  Lower end of the arc: x2=22 y2=20
  </code></pre>
  <p>Now I want to write an absolute path:</p>
  <pre><code>&lt;path d=&quot;M xx yy 
           A rx ry x-axis-rotation large-arc-flag sweep-flag x y&quot;/&gt;
  </code></pre>
  <p>This seems to be a hard task but I'm sure there is a way to derive everything from the givens.</p>