Let $\bar{a}, \bar{b}$ and $\bar{c}$ be three vectors having magnitudes $1, 1$ and $2$ respectively. If $\bar{a} \times(\bar{a} \times \bar{c})+\bar{b}=\bar{0}$,then the acute angle between $\bar{a}$ and $\bar{c}$ is

Let $\vec{a}=2 \hat{i}+3 \hat{j}+4 \hat{k}, \vec{b}=2 \hat{i}-2 \hat{j}-2 \hat{k}$ and $\vec{c}=-\hat{i}+4 \hat{j}+3 \hat{k}$. If $\vec{d}$ is a vector perpendicular to both $\vec{b}$ and $\vec{c}$ and $\vec{a} \cdot \vec{d}=18$,then $|\vec{a} \times \vec{d}|^2$ is equal to $..........$.

Let $\bar{a}=\hat{i}+\hat{j}+\hat{k}$,$\bar{b}$ and $\bar{c}=\hat{j}-\hat{k}$ be three vectors such that $\bar{a} \times \bar{b}=\bar{c}$ and $\bar{a} \cdot \bar{c}=0$. If the length of the projection vector of the vector $\bar{b}$ on the vector $\bar{a} \times \bar{c}$ is $l$,then the value of $3l^2$ is

Let $\vec{a}=2 \hat{i}-\hat{j}+2 \hat{k}$ and $\vec{b}=\hat{i}+2 \hat{j}-\hat{k}$. Let a vector $\vec{v}$ be in the plane containing $\vec{a}$ and $\vec{b}$. If $\vec{v}$ is perpendicular to the vector $\vec{c}=3 \hat{i}+2 \hat{j}-\hat{k}$ and its projection on $\vec{a}$ is $19 \text{ units}$,then $|2 \vec{v}|^{2}$ is equal to .... .

If $u = i \times (a \times i) + j \times (a \times j) + k \times (a \times k),$ then

Let $\overline{a}, \overline{b}, \overline{c}$ be three non-zero vectors,such that no two of them are collinear and $(\overline{a} \times \overline{b}) \times \overline{c} = \frac{1}{3}|\overline{b}||\overline{c}| \overline{a}$. If $\theta$ is the angle between the vectors $\overline{b}$ and $\overline{c}$,then the value of $\sin \theta$ is