If the angle between a and b is (π)/3 and | a × b |=3 √ 3, then the value of a · b is

If the angle between $\displaystyle \overrightarrow{\mathrm{a}}$ and $\displaystyle \overrightarrow{\mathrm{b}}$ is $\displaystyle \frac{\pi}{3}$ and $\displaystyle |\overrightarrow{\mathrm{a}} \times \overrightarrow{\mathrm{b}}|=3 \sqrt{3}$, then the value of $\displaystyle \overrightarrow{\mathrm{a}} \cdot \overrightarrow{\mathrm{b}}$ is