Answer
$4\pi$ cm
Work Step by Step
We know that the length of the arc $s$ cut off by $\theta$ can be calculated as $s=r\theta$.
We are given that $\theta=\frac{\pi}{3}$ and $r=12$ cm.
Therefore, $s=\frac{\pi}{3}(12)=\frac{\pi}{3}\times12=\frac{\pi\times12}{3}=\frac{12\pi}{3}=4\pi$ cm.