Our calculus teachers have found that many of the students who sign up for calculus do not have the level of mathematical sophistication in doing algebra problems that is needed. In algebra and trig courses, students often focus on one or two techniques at a time, learning to do problems with those techniques, and don't fit those into an overview of working problems in general. One of the main objectives of a precalculus course is to give students experience working problems where they have to put together a plan using techniques from different parts of their previous courses.
Here is a Review Sheet that one of our excellent calculus teachers uses to indicate the level of sophistication needed for calculus. This is long, so you may find it tedious to do it all. But all the problems are important. At least look over these and see whether you remember having done problems at this level of sophistication in your precalculus course.
Trigonometry is a particular challenge. It is not a hard topic, in general, but it looks enough different from algebra that students find it intimidating if they haven't used it periodically to keep their skills fresh. To review trig in particular, you can look over our list of trig facts that all students should have memorized at one point. Now you should still remember many of them, and, for the rest, you should at least remember how to recognize when you need to use them know where to look them up when you need to review them.
Here's a page that gives some hints about the relationships between the various formulas in trig. Here's a guide to using this page.
Last revised November 28, 2008 . Questions, suggestions, comments? (old review sheet)