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

A person moved from $A$ to $B$ on a circular path as shown in figure. If the distance travelled by him is $60 \,m$, then the magnitude of displacement would be$.....\,m$ (Given $\left.\cos 135^{\circ}=-0.7\right)$

Explain the parallelogram method for vector addition. Also explain that this is comparable to triangle method.

 $\overrightarrow A \, = \,3\widehat i\, + \,2\widehat j$ , $\overrightarrow B \, = \widehat {\,i} + \widehat j - 2\widehat k$  then find their addition by algebric method.

Three forces given by vectors $2 \hat{i}+2 \hat{j}, 2 \hat{i}-2 \hat{j}$ and $-4 \hat{i}$ are acting together on a point object at rest. The object moves along the direction

Two vectors $P = 2\hat i + b\hat j + 2\hat k$ and $Q = \hat i + \hat j + \hat k$ will be parallel if $b=$ ........