Answer:
x = 2πn - π/3
x = 2πn + π/3
Explanation:
Given that a trigonometric equation
cos x =

We know that,
cos x = -

Now take the inverse of cos both the side
x = -π/3
We know that, the cycle of cos is 2π
So, we add 2πn where n is any integer.
x = 2πn - π/3
x = 2πn + π/3
That's the final answer,
I hope it will help you.