Answer
$y=\cos (x-\frac{\pi}{3})$
Work Step by Step
The graph is that of $y=\cos x$ except that it has been translated $\frac{\pi}{3}$ units to the right.
Cosine graphs that are translated right or left are of the form $y=\cos (x-d)$. According to the rules of translating graphs, if the translation is $d$ units to the right, $d$ is greater than zero. Conversely, if the translation is $|d|$ units to the left, $d$ is less than zero.
Therefore, as the graph has been translated $\frac{\pi}{3}$ units to the right, $d=\frac{\pi}{3}$. Therefore, its equation is $y=\cos (x-\frac{\pi}{3})$.
