title: How do I get the "reverse" tangent in objective-c?
body: <p>I know that <code>tan(angle)</code> gets me the tangent. But how do I do the "reverse tangent" so that I can get the angle given the length of both sides of the right triangle?</p>
  
  <p>I'm assuming there is a method for this in <code>math.h</code>?</p>