Question

The resultant of $\overrightarrow{P}$ and $\overrightarrow{Q}$ is perpendicular to $\overrightarrow{P}$. What is the angle between $\overrightarrow{P}$ and $\overrightarrow{Q}$.

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

$\Rightarrow$ tan${90}^{\circ }$ = $\frac{Qsin\theta }{P+Qcos\theta }$ $\Rightarrow$ P + Q cos $\theta$ = 0
cos $\theta$ = $\frac{-P}{Q}$ $\therefore$ $\theta$ = ${cos}^{-1}$($\frac{-P}{Q}$)