Q. If |$\overrightarrow{\mathbf{a}}| = 10,|\overrightarrow{\mathbf{b}}| = 2\$and$\ \overrightarrow{\mathbf{a}} \bullet \overrightarrow{\mathbf{b}} = 12$ then $|\overrightarrow{\mathbf{a}} \times \overrightarrow{\mathbf{b}}|$ is equal to

A) 12
B) 14
C) 16
D) 18
Explanation

(c)
Given, $\overrightarrow{\mathbf{a}} \bullet \overrightarrow{\mathbf{b}} = 12$
$\Longrightarrow \left| \overrightarrow{\mathbf{a}} \right||\overrightarrow{\mathbf{b}}|$ $cos\ \theta\ = 12$
$\Longrightarrow 10 \times 2 \times \cos{\theta = 12}$
$\Longrightarrow \cos\theta = \frac{3}{5}$
$\therefore\sin\theta = \sqrt{1 - {cos\ }^{2}\theta} = \sqrt{1 - \frac{9}{25}} = \frac{4}{5}$
$Now,\ \$
$|\overrightarrow{\mathbf{a}} \times \overrightarrow{\mathbf{b}}| = |\overrightarrow{\mathbf{a}}||\overrightarrow{\mathbf{b}}|\ sin\ \theta = 10 \times 2 \times \frac{4}{5} = 16$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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