Find a vector of magnitude 9 units and perpendicular to the vectors and . [Application]

Find a vector of magnitude 9 units and perpendicular to the vectors $\vec{a} = 4\hat{i} - \hat{j} + \hat{k}$ and $\vec{b} = -2\hat{i} + \hat{j} - 2\hat{k}$. [Application]