You can use these in any way you find useful, but successfully solving the problems is more likely to help you than passively watching the review and solutions.

Please note that this is a concise review intended for students who have already studied trigonometry, and who have either forgotten the material or didn't fully understand it the first time. Students who have never seen trig before may be better off taking Math 50 and 60 (a two-semester version of Math 90 that includes trigonometry and other precalculus topics), or obtaining a book on trigonometry and studying the material independently.