If the square of the resultant of two forces of equal magnitude is equal to three times their product,then the angle between them is ........ $^o$.

For two vectors $\vec{a}$ and $\vec{b}$,if $|\vec{a} + \vec{b}| = |\vec{a} - \vec{b}|$,then the angle between $\vec{a}$ and $\vec{b}$ is:

$A$ force of $6\,N$ and another of $8\,N$ can be applied together to produce the effect of a single force of $..........\,N$

When are the magnitudes of $\vec{A} + \vec{B}$ and $\vec{A} - \vec{B}$ equal?

What vector must be added to the two vectors $\hat{i} - 2\hat{j} + 2\hat{k}$ and $2\hat{i} + \hat{j} - \hat{k}$ so that the resultant may be a unit vector along the $X$-axis?

$\overrightarrow{A}$ and $\overrightarrow{B}$ are two vectors of equal magnitudes and $\theta$ is the angle between them. The angle between $\overrightarrow{A}$ or $\overrightarrow{B}$ with their resultant is