2
votes
2answers
2k views

How to simplfiy $ \cos^{2}(\theta) \sin(\theta) $ to terms of $\sin$ or $\cos$ only?

Is it possible to simplify $$ \cos^{2}(\theta) \sin(\theta) $$ to terms of only $\sin$ or $\cos$? I need to simplify this to take the integral.
4
votes
6answers
225 views

Help me to remember $\operatorname{cosh}^{2}(y) -\operatorname{sinh}^{2}(y)=1$, some easy verification and deduction?

I can faintly visualize some way of deducing this formula with exponential functions but forgot it. How do you remember it? Suppose you just forget whether it is plus-or-minus there, how do you find ...
11
votes
3answers
3k views

Why is it that when proving trig identities, one must work both sides independently?

Suppose that you have to prove the trig identity: $$\frac{\sin\theta - \sin^3\theta}{\cos^2\theta}=\sin\theta$$ I have always been told that I should manipulate the left and right sides of the ...
2
votes
2answers
325 views

Good SAT learning resources?

I'm looking to brush up on SAT math. (That's basic algebra, probability and trigonometry.) I'm interested in books and websites.