Trig Identity proving..............

(1 - tan(x)) / (1 + tan(x)) ==== (cos(x) - sin(x)) / (cos(x) + sin(x))

I'm stuck on proving this one.

You get -(sin(x)-cos(x))/(sin(x)+cos(x)) using tan(x) = sin(x) / cos(x).

DID you even try tan x = sin x / cos x ??? and doing the algebra ???