cos(2x) cos(x) - sin(2x) sin(x)...what are the possible solutions for this x is greater than or equal to 0 but less than 360

Question

cwrw238 · Answer

use the identity  cos(A +B) = cosAcosB-sinAsinB

xapproachesinfinity · Answer

i don't see an equation here?

cwrw238 · Answer

no - just noticed that!
 where's the '=' ??

xapproachesinfinity · Answer

Shoot! op throw me off the the thread hehe
so yes we need = something equal to something for us to solve

xapproachesinfinity · Answer

$cos2xcosx-sin2xsinx=cos(3x)$ that's for thr left hand side
we need to know the right hand side of the equation? you didn't write it

cwrw238 · Answer

we can't help you any further unless you can give us that

xapproachesinfinity · Answer

You haven't post the question yet lol

anonymous · Answer

oh that would be = to 0..sorry I forgot

xapproachesinfinity · Answer

oh hehehe the equation has to always have to equal sides 
otherwise it is not an equation lol
anyways so we have $\huge cos2xcosx-sin2xsinx=0$

xapproachesinfinity · Answer

As I said above the left hand side is
$\large \rm cos2xcosx-sin2xsinx=cos(2x+x)=cos(3x)$

xapproachesinfinity · Answer

I used the identity of sum of two angles like @cwrw238  mentioned above

xapproachesinfinity · Answer

so i got $\huge \rm cos(3x)=0$

anonymous · Answer

thank you guys, I already got the right answer...

xapproachesinfinity · Answer

Now solve for x

xapproachesinfinity · Answer

oh ok! np

xapproachesinfinity · Answer

Hit best answer thingy if you are satisfied -_^