The acute angle between the vector $2\hat{i} + \hat{j} - 3\hat{k}$ and the plane containing the vectors $2\hat{i} + 3\hat{j} - \hat{k}$ and $\hat{i} - \hat{j} + 2\hat{k}$ is

A parallelogram is constructed on $5\bar{a} + 2\bar{b}$ and $\bar{a} - 3\bar{b}$ as its adjacent sides, with $|\bar{a}| = 2\sqrt{2}, |\bar{b}| = 3$ . The angle between $\bar{a}$ and $\bar{b}$ is $\dfrac{\pi}{4}$ . Then the length of the diagonals of the parallelogram are

A unit vector coplanar with $\hat{i} + \hat{j} + 2\hat{k}$ and $\hat{i} + 2\hat{j} + \hat{k}$ and perpendicular to $\hat{i} + \hat{j} + \hat{k}$ is

If $\vec{a} + \vec{b} + \vec{c} = \vec{0}$, $|\vec{a}| = |\vec{b}| = |\vec{c}| = 3$ and $\theta$ is the angle between $\vec{b}$ and $\vec{c}$ then $\tan^2\theta + \cot^2\theta =$