Answer
The statement does not make sense.
Work Step by Step
We know that the equation is already in the form of an isolated trigonometric function on one side and a constant form on another side.
Therefore, the value of $x$ can easily be found by using $\cos \pi =-1$
$\begin{align}
& \cos \left( x-\frac{\pi }{3} \right)=\cos \pi \\
& x-\frac{\pi }{3}=\pi \\
& x=\pi +\frac{\pi }{3} \\
& x=\frac{4\pi }{3}
\end{align}$
Thus, the equation can be simply solved by using the trigonometric identity. So, there is a need to apply the difference formula of $\cos $.
