if cos x = -1/3, what is the value of cos 2x
it also says "note (cos x)^2 = 1+cos2x/2
can you explain this to me and what topic it is
@xxupenngal using that identity, solve for cos 2x in terms of cos x. You can then plug in to find the value of cos 2x.
Have you taken trig? Or a course that uses trig?