Question

Given that both $P$ and $Q$ are greater than 1. The magnitude of $\overrightarrow{P}\times \overrightarrow{Q}$ cannot be

• A. equal to $PQ$
• B. less than $PQ$
• C. more than $PQ$
• D. equal to $P/Q$.

Answer 1

Answer: (C)

$|\overrightarrow{P}\times \overrightarrow{Q}|$ = PQ sin $\theta$ and sin $\theta \le$ 1
Also PQ sin $\theta$ can be equal to P/Q when sin $\theta =1/Q^2$.
Thus (1), (2) and (4) are correct but (3) is not possible.