I can, for the mort part, understand how to derive and "proof" most of my Identity work, but some of the more complex (in my feeble opinion) problems give me quite a bit of trouble. Can anyone explain these? "Use the fundamental identities to simplify to sines and cosines: tan(^2)x - (csc(^2)x/cot(^2)x) " Someone told me the answer was (-1) and I had no idea how to get that. and "Confirm the Identity: (sinx)/(1-cosx) + (sinx)/(1+cosx) = 2cscx" Any explanations would be greatly appreciated! Thanks!