Question

Verifying this is an Identity:

tan(u+v/2) = (sin u + sin v)/(cos u + cos v)

Here's what I have so far,
tan(u+v/2) = (sin u + sin v)/(cos u + cos v)

(1/2)tan(u+v) =

2(1/2)(tan u + tan v/1-tan u + tan v)(2) = to get

2(tan u + tan v)/(1-tan u + tan v) =

(2 tan u + 2 tan v)/(1-tan u + tan v) =

This point I am stuck on what to do next.