Question

If $A = B + C$ have scalar magnitudes of $5,4,3$ units respectively, then the angle between $A$ and $C$ is

• A. $\cos^{-1} \left(\frac{3}{5}\right)$
• B. $\cos^{-1} \left(\frac{4}{5}\right)$
• C. $\frac{\pi}{2}$
• D. $\sin^{-1}\left(\frac{3}{4}\right)$

Answer 1

Answer: (A)

Here, triangle is

$\theta=\cos ^{-1}\left(\frac{| C |}{| A |}\right)$
$\theta=\cos ^{-1}\left(\frac{3}{5}\right)$