\[6\sqrt{\frac{2}{3}} = \sqrt{36 \cdot \frac{2}{3}} = \sqrt{12 \cdot 2} = \sqrt{24};\]
\[\frac{1}{2} \cdot \sqrt{88} = \sqrt{88 \cdot \frac{1}{4}} = \sqrt{22};\]
\[\sqrt{24} > \sqrt{22}\]
\[6\sqrt{\frac{2}{3}} > \frac{1}{2}\sqrt{88}.\]