title: How to get the Original Value of Sin in Javascript?
body: <p>Im assigning a value like this:</p>
  <p><code>var c = 1.2; var X = 0.3; var y = (c * Math.sin(X));</code></p>
  <p>I then make some changes to value y like:</p>
  <pre><code>y += 0.5;
  </code></pre>
  <p>How can i now get the new value of X using only y and c, such that it satisfies the original equation <code>y = (c * Math.sin(X))</code>.</p>