(a) If the vectors $\overrightarrow{\mathrm{a}}$ and $\overrightarrow{\mathrm{b}}$ are such that $\left|\overrightarrow{\mathrm{a}}\right|=3,|\overrightarrow{\mathrm{b}}|=\frac{2}{3}$ and $\overrightarrow{\mathit{a}}\times \overrightarrow{\mathit{b}}$ is a unit vector, then find the angle between $\overrightarrow{\mathit{a}}$ and $\overrightarrow{\mathit{b}}$.
OR
(b) Find the area of a parallelogram whose adjacent sides are determined by the vectors $\overrightarrow{\mathit{a}}=\hat{\mathit{i}}-\hat{\mathit{j}}+3\hat{\mathit{k}}$ and $\overrightarrow{\mathit{b}}=2\hat{\mathit{i}}-7\hat{\mathit{j}}+\hat{\mathit{k}}$.