Question:
If $\bar{P} \times \bar{Q}=\vec{Q} \times \vec{P}$, the angle between $\bar{P}$ and $\bar{Q}$ is $\theta\left(0^{\circ}<\theta<360^{\circ}\right)$. The value of ' $\theta$ ' will be
Solution:
(180)
If $\vec{P} \times \vec{Q}=\vec{Q} \times \bar{P}$
Only if $\vec{P}=0$
Or $\overrightarrow{\mathrm{Q}}=0$
The angle b/w $\overrightarrow{\mathrm{P}} \& \overrightarrow{\mathrm{Q}}$ is $\theta\left(0^{\circ}<\theta<360^{\circ}\right)$
So $\theta=180^{\circ}$