Answer
$r= 2\ cm$
Work Step by Step
The formula used to determine the sector area for any central angle is $A_{s}=\frac{\theta}{360}\times\pi({r^2)}$
where $A_{s}$ is the area of the sector and $r$ is the radius of the circle
Given
Central angle $(\theta)=30^{\circ}$
Area = $\frac{\pi}{3} sq\ cm$
using the above formula
$\frac{\pi}{3}=\frac{30}{360}\times\pi\ r^2$
$r^2=4$
$r=\sqrt 4$
$r = 2 \ cm$
