Hello FlabbyRoach Originally Posted by

**FlabbyRoach** Thank You.

Could you explain how to reverse the equation to find that answer?

Thanks again.

FlabbyRoach

No, I'm afraid I can't. It's not possible to get an analytical solution to an equation like:

$\displaystyle \tan\theta-\theta = k$,

which is what your equation is - where $\displaystyle \theta$ is an angle measured in radians, and $\displaystyle k$ is a constant.

The best you can do is to use a numerical method to get an approximation to the answer. As I said, I used Excel, which has a Goal Seek facility. This usually enables you to get an accurate answer to a problem like this very quickly - although in this case, the answer wasn't very accurate, so I refined it manually, using basically a 'trial and error' process to home in on the answer.

It sounds a bit unsatisfactory, but it's actually very quick and easy to do.

Grandad