Q. Let $\overrightarrow{\mathbf{a}}$ and $\overrightarrow{\mathbf{b}}$ be two unit vectors such that angle between them is $60{^\circ}$. Then, $|\overrightarrow{\mathbf{a}}\mathbf{-}\overrightarrow{\mathbf{b}}|$ is equal to

A) $\sqrt{5}$
B) $\sqrt{3}$
C) 0
D) 1
Explanation

(d)
$\left| \overrightarrow{\mathbf{a}}\mathbf{-}\overrightarrow{\mathbf{b}} \right|^{2} = \left| \overrightarrow{\mathbf{a}}\left. \ \right|^{2} + \right|\overrightarrow{\mathbf{b}}\left. \ \right|^{2} - 2\ \left| \overrightarrow{\mathbf{a}} \right|\left| \overrightarrow{\mathbf{b}} \right|\cos\theta$
$\Rightarrow \ \left| \overrightarrow{\mathbf{a}}\mathbf{-}\overrightarrow{\mathbf{b}} \right|^{2} = 1 + 1 - 2\cos{60{^\circ} = 2 - 1}$
$\Rightarrow |\overrightarrow{\mathbf{a}}\mathbf{-}\overrightarrow{\mathbf{b}}| = 1$

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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