[Dan Zollman]

I thought a bit more about that equation and realized that the equation is incorrect. I should withdraw what I posted because I'm not sure if my method was correct.

I now think that the equation should use inverse tangent instead of inverse sine, but please don't use it at all until someone can provide a second opinion. Sorry if it misled you.

I'll come back to it tomorrow when I'm less tired and see if I can come up with a more solid solution.