If vectors $P, Q$ and $R$ have magnitude $5, 12$ and $13 $ units and $\overrightarrow P + \overrightarrow Q = \overrightarrow R ,$ the angle between $Q$ and $R$ is
${\cos ^{ - 1}}\frac{5}{{12}}$
${\cos ^{ - 1}}\frac{5}{{13}}$
${\cos ^{ - 1}}\frac{{12}}{{13}}$
${\cos ^{ - 1}}\frac{7}{{13}}$
The vectors $\vec{A}$ and $\vec{B}$ are such that
$|\vec{A}+\vec{B}|=|\vec{A}-\vec{B}|$
The angle between the two vectors is
If $| A + B |=| A |+| B |$ the angle between $\overrightarrow A $and $\overrightarrow B $ is ....... $^o$
Give the names of two methods for vector addition. Write the law of parallogram for vector addition.