Try double angle formula
I guess Trigonometry question go in the Trigonometry section. That makes sense.
I was having trouble with this question (See attachment) as I'm not sure how to change it into a sum or something similar to find the general solution. Iím not sure if I need to use identities or a product to sum formula or something similar. If someone could work me through it, it would be greatly appreciated.
I'm not sure how to use the double angle formula a second time and then factorise it. It would be helpful if you could show me how to do that and then showhow to factorise it.
wow, really nice work mr_fantastic
btw, I mean like this :
2sin2xcos2x-cosx = 0
4 sin x cos x cos 2x - cos x = 0
(cos x) (4 sin x cos 2x - 1 ) = 0
cos x = 0 or 4 sin x cos 2x - 1 = 0
Use the double angle formula again on cos 2x and state the equation in term of sin x
but mr_fantastic has given a really elegant way