Question

If the resultant of two vectors $\overset{\rightarrow}{A}$ and $\overset{\rightarrow}{B}$ is perpendicular to $\overset{\rightarrow}{A}$, then the angle between $\overset{\rightarrow}{A}$ and $\overset{\rightarrow}{B}$ is -

• A. (a) tan^–1$\left( - \frac{A}{B} \right)$
• A. (b) sin^–1$\left( \frac{A}{B} \right)$
• A. (c) tan^–1$\left( \frac{A}{B} \right)$
• A. (d) cos^–1$\left( - \frac{A}{B} \right)$

Answer 1

(d)

$(\overset{\rightarrow}{A} + \overset{\rightarrow}{B}).\overset{\rightarrow}{A}$ = 0

A² + AB cos q = 0

A² = – AB cos q

q = cos^–1$\left( - \frac{A}{B} \right)$