1. ## Trig identity problem

I have a problem as follows:

cos((π/3) - X)

I then used the addition identity of cos(x-y) = cos x cos y + sin x sin y and got:

cos(π/3)*cosX + sin(π/3)*sinX

Then i used the unit circle to get

(1/2)*cosX + √(3)*sinX

And am now stuck. I'm supposed to solve for 'x' but i'm not sure how to continue.
2. you cannot solve for $x$ unless $\cos (\pi/3 - x)$ is equated to some value..