The value of the sum of two vectors $\overrightarrow A $ and $\overrightarrow B $ with $\theta $ as the angle between them is
$\sqrt {{A^2} + {B^2} + 2AB\cos \theta } $
$\sqrt {{A^2} - {B^2} + 2AB\cos \theta } $
$\sqrt {{A^2} + {B^2} - 2AB\sin \theta } $
$\sqrt {{A^2} + {B^2} + 2AB\sin \theta } $
A body moves due East with velocity $20\, km/hour$ and then due North with velocity $15 \,km/hour$. The resultant velocity..........$km/hour$
A particle is simultaneously acted by two forces equal to $4\, N$ and $3 \,N$. The net force on the particle is
Two forces having magnitude $A$ and $\frac{ A }{2}$ are perpendicular to each other. The magnitude of their resultant is
The resultant of two vectors $\overrightarrow P $ and $\overrightarrow Q $ is $\overrightarrow R .$ If $Q$ is doubled, the new resultant is perpendicular to $P$. Then $R $ equals