The unit vector in the direction of the vector $(1, 0, 0)$ is $.......$

If the position vectors of the points $A, B, C$ are $i + j$,$i - j$,and $a i + b j + c k$ respectively,then the points $A, B, C$ are collinear if

If the magnitudes of $\bar{a}$,$\bar{b}$ and $\bar{a}+\bar{b}$ are respectively $3$,$4$ and $5$,then the magnitude of $\bar{a}-\bar{b}$ is

If $|\vec{a}| = 2$,$|\vec{b}| = 3$ and $|2\vec{a} - \vec{b}| = 5$,then $|2\vec{a} + \vec{b}|$ equals

If $\vec{a} = \vec{b}$,then............

Let $O$ be the origin and the position vectors of $A$ and $B$ be $2 \hat{i}+2 \hat{j}+\hat{k}$ and $2 \hat{i}+4 \hat{j}+4 \hat{k}$ respectively. If the internal bisector of $\angle AOB$ meets the line $AB$ at $C$,then the length of $OC$ is