To find volume $ V $ use formula:
$$ V = \dfrac{ h ^{ 2 } \cdot r \cdot \pi}{ 3 } $$After substituting $r = 3\, \text{cm}$ and $h = 2 \sqrt{ 3 }\, \text{cm}$ we have:
$$ V = \dfrac{ 12\, \text{cm}^2 \cdot 3\, \text{cm} \cdot \pi}{ 3 }$$$$ V = \dfrac{ 36\, \text{cm}^3 \, \pi}{ 3 } $$$$ V = 12\pi\, \text{cm}^3 $$