Two forces of magnitudes $3 \, N$ and $4 \, N$ are acting on an object. If the angle between them is $90^\circ$,then their resultant force is ... $N$.

If $|\vec{A} + \vec{B}| = |\vec{A}| = |\vec{B}|$,then the angle between $\vec{A}$ and $\vec{B}$ is ............ $^o$.

Two forces,each of magnitude $F$,have a resultant of the same magnitude $F$. The angle between the two forces is....... $^o$

If for two vectors $\overrightarrow{A}$ and $\overrightarrow{B}$,the sum $(\overrightarrow{A} + \overrightarrow{B})$ is perpendicular to the difference $(\overrightarrow{A} - \overrightarrow{B})$,then the ratio of their magnitudes is:

The vector sum of two forces is perpendicular to their vector difference. In this case,the forces:

With respect to a rectangular cartesian coordinate system,three vectors are expressed as $\vec a = 4\hat i - \hat j$,$\vec b = -3\hat i + 2\hat j$,and $\vec c = -\hat k$,where $\hat i, \hat j, \hat k$ are unit vectors along the $X, Y,$ and $Z$-axis respectively. The unit vector $\hat r$ along the direction of the sum of these vectors is: