Q. What is the angle between $\widehat{i} + \widehat{j} + \widehat{k}$ and $\widehat{i}$
A) $0{^\circ}$
B) $\pi/6$
C) $\pi/3$
D) None of these
Explanation
(d) $\overrightarrow{A} = \widehat{i} + \widehat{j} + \widehat{k};A = \sqrt{1^{2} + 1^{2} + 1^{2}} = \sqrt{3}$
cos$\theta = \frac{\overrightarrow{A}.\widehat{i}}{\sqrt{3}} = \frac{1}{\sqrt{3}} = \frac{\sqrt{3}}{3}$
$= \frac{1.732}{3} = 0.5773 = \cos 54{^\circ}44'$
$\theta = 54{^\circ}44'$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.