Help finding the derivative

f(x)= (sec x)/ (1+sec x)

what will the derivative be and how? full points for the answer and explanation

use the quotient rule:

f ' (x) = (1+sec x)*(sec x tan x) - [sec x tan x (sec x)] / (1+ sec x)^2

I formatted it better and in more detailed here: http://snag.gy/TyXAH.jpg

This can be rewritten as (1/cos x)/[(cos x + 1)/cos x]
That simplifies to 1/(cos x + 1).
Let's do quotient rule.
[(cos x + 1)(0) - (1)(-sinx)]/(cos x + 1)^2
So answer = sin x/(cos x + 1)^2