I think I might cause more confusion than necessary if I try to help you with the more complicated ones that should use the series forms / identities.

There are other smarter math guys here, I'll back off and see if anyone can pick this up.

But maybe, knowing what you know now, you should try doing those problems by hand the long way without identities to get a better understanding??

if your proff said "use technology" then I can help with calculator syntax and whatnot.

I'll try the rest of the problems and keep up with the thread.