harder 3u help? (1 Viewer)

[browntown]

im doin q9.2 in excel math ext II book..

question is
Find the general solution of the equation sin 2x + sin 3x + sin 4x = 0, and hence write down the particular solution in the interval 0=<x=><2x

anyway im working thru the solutions
rewrite eqn
(sin 4x + sin 2x) + sin 3x = 0

then its got use the identity
sin A + sin B = 2sin(1/2(A + B))cos(1/2(A - B))

and i do that and get
2sin 3x*cos x + sin 3x = 0

but they hav got
2sin 3x*cos 2x + sin 3x = 0

mayb im just tired or cant subtract or sumthin.. but wat am i missin..</x=>

 

[SoulSearcher]

Your working out doesn't look wrong.

 

[browntown]

so im not crazy.. sad thing is that only the start of the question..

 

[zeek]

maybe the question is wrong... move onto another one and check if you get that one right.

 

[Naylyn]

My excel book says that as well.
It looks like they are wrong to me.