Do I need to know the double and half angle trig formulas for the Math II SAT Subject Test? What about other trigonometric identities?
Trigonometric identities typically make up about four percent of the questions on the Math II SAT Subject Test, so you should know them if you're hoping to get a score in the 700 to 800 range. Just don't spend too much time memorizing them since they make up such a small proportion of the test. Here's a list of trigonometric identities: http://www.sosmath.com/trig/Trig5/trig5/trig5.html. I would say that you can ignore the Sum-to-Product and Product-to-Sum sections, but the rest of the identities on the list are fair game for the test.