Trig problem

[Cannon]

I need help solving this equation for x. I can only get this far:
3cos²x -2cosx - 1 = 0

I know, doesnt seem far but I just don't know what to do as the next step. Could someone please help me out? Thanks.

[KatieB]

This is a quadratic in cos(x), which you can solve for cos(x)

(3cos(x) + 1)(cos(x) - 1) = 0

Therefore, cos(x) = -1/3 or 1

You should be able to do the rest from here!