Once again, I need help on some trigonometric equations.
If cos(x)=-3/5, and pi/2 < x < 3pi/2, find sin(x/2)
Rewrite as product: sin3y-sin4y
If sin2x-cosx=0, find all the solutions in the interval [0, 2pi).
Thanks.
(If I don't respond it's because I've fallen asleep)
hmm
Formulae you can learn and that will be useful =)
For the last 2 ones, you can remember that the cosine is always racist, so it will be a product of cosines only or sines only. It goes the same way for the addition formula, cosines remain with cosines and so do sines.
Here, just use the second formula
You can try to demonstrate them ^^
rewrite :If sin2x-cosx=0, find all the solutions in the interval [0, 2pi).
Thanks.
(If I don't respond it's because I've fallen asleep)
So you have to solve :
Can you take it from here ?