Originally Posted by

**Skizye** So I've been looking at this homework that's due tommorrow for a grade for the past hour and I can't seem to figure these out.

1. $\displaystyle sin^3x - cos^3x = (1 + sinx cosx)(sinx - cosx)$

2. $\displaystyle (1/(siny - 1)) - (1/(siny + 1)) = -2sec^2y$

3. $\displaystyle 1 - 2sin^2r + sin^4r = cos^4r$

4. $\displaystyle tanu + (cosu/(1 + sinu)) = secu$

5. $\displaystyle (tanx + secx)/(secx - cosx + tanx) = cscx$

If I could get a hint or something on how to do these I would appreciate it, I don't want to ask anyone to do my homework for me (although I won't complain if you show me the whole problem) but I don't even know where to start on these problems. Thanks!