Question

The magnitudes of vectors $\overrightarrow{A},\overrightarrow{B}$and$\overrightarrow{C}$are 3, 4 and 5 units respectively. If $\overrightarrow{A} + \overrightarrow{B} = \overrightarrow{C}$, the angle between $\overrightarrow{A}$and $\overrightarrow{B}$is

• A. $\frac{\pi}{2}$
• B. $\cos^{- 1}(0.6)$
• C. $\tan^{- 1}\left( \frac{7}{5} \right)$
• D. $\frac{\pi}{4}$

Answer 1

Answer: (A)

$\frac{\pi}{2}$

Answer 2

$C = \sqrt{A^{2} + B^{2}}$

=$\sqrt{3^{2} + 4^{2}} = 5$

$\therefore$ Angle between $\overset{\rightarrow}{A}$ and $\overset{\rightarrow}{B}$ is $\frac{\pi}{2}$