can someone please show me how to establish this identity?
1+sin(a)+cos(a) / 1+sin(a)-cos(a) = 1+cos(a) / sin(a)

Group some terms and 'rationalise'

\frac{(1+sinA) + cosA}{(1-sinA) - cosA} = \frac{(1+sinA) + cosA}{(1+sinA) - cosA} \times \frac{(1+sinA) + cosA}{(1+sinA) + cosA}

Take do this and simplify. You should be getting close to the solution easily enough. Post what you get! :)