What should I review on Trigonometry for preparation for my placement test at college?

Question

I am going to take a placement test at college, and there will be math questions. I am pretty good at algebra but I am afraid of trigonometry since I forgot most of it's formulas. Now I have short time (less than a week) and I need to brush myself up for this. Now what do you suggest me to study on trigonometry? All the basic rules? Need help on this, thanks!

Answer 1

Basic Rules for Trig - Memorize all these:
1) tan x = sin x / cos x
2) cot x = cos x / sin x
3) sec x = 1 / cos x
4) csc x = 1 / sin x
5) (prob most important) cos^2 x + sin^2 x = 1
6) sin (x+y) = sin x cos y + cos x sin y
7) cos (x + y) = cos x cos y - sin x sin y
(note: you can use the previous two to find out sin 2x and cos 2x since 2x = x + x.)
8) for a triangle with angles A, B, and C and opposite sides a, b, and c, respectively, sin A / a = sin B / b = sin C / c
9) c^2 = a^2 + b^2 - 2ab cos C

Try to remember those formulas ( the top 7 at the very least) and you should be fine. Good luck!