posted by Hannah .
Perform the multiplication and use the fundamental identities to simplify.
(cotx + cscx)(cotx-cscx)
I know that you have to foil first so
cot^2x - csc^2x and then use the pythagorean identity 1+cot^2u = csc^2u but I do not know how to simplify.
You have the solution right there in front of you ...
cot^2x - csc^2x
= cot^2x - (1 + cot^2x)
= cot^2x - 1 - cot^2x
= - 1