I don't quickly see an answer using theorems I have memorized; but the equation reminds me of the Law of Tangents, as well as other formulas involving tangents of half angles in a triangle. Have you learned any of these less-well-known facts, such that you might be expected to recognize it on sight?

In the absence of such a specialized trick, I would probably start with the half-angle formula for the tangent. In fact, having just tried that out, I see the answer quickly.

Show us some work using this idea.