Question

What is the angle between $\overrightarrow{P}\times \overrightarrow{Q}$ and $\overrightarrow{Q}\times \overrightarrow{P}$ ?

• A. zero
• B. $\pi /2$
• C. $\pi$
• D. none of the above

Answer 1

The correct option is C $\pi$

Assume that

$\overrightarrow{P}in\hat{i}$

$\overrightarrow{Q}in\hat{j}$

Then,

$\overrightarrow{P}\times \overrightarrow{Q}\to \overrightarrow{K}$

$\overrightarrow{Q}\times \overrightarrow{P}\to -\overrightarrow{K}$

$\Rightarrow$ So angle between $\overrightarrow{P}\times \overrightarrow{Q}$ and $\overrightarrow{Q}\times \overrightarrow{P}$ is $\pi$

so option $C$ is correct.