You may want to look at Brown's
Advanced Math. It derives a lot of the identities, and has a lot in the way of explanation.
Thanks-- found a used copy in a neighboring state for just about $5. It should be here next week.
Similarly, a Schaum's outline for Precalc, which I
hope will be helpful. Naturally, the sections on polar coordinates and conics aren't preview pages on Amazon, so I have no real way of knowing at the moment. Grr.
The mismatch between the instructional and resource material and the level of the
assessments is nothing short of astonishing to me, in all seriousness.
First quiz in this unit made me go--
Which was better than DD's response, which was more along the lines of
