Q. The angle between the $z$-axis and the vector $\widehat{i} + \widehat{j} + \sqrt{2}\widehat{k}$ is
A) 30${^\circ}$
B) 45${^\circ}$
C) 60${^\circ}$
D) 90${^\circ}$
Explanation
(b) $cos\theta = \frac{\left( \widehat{k} \right).(\widehat{i} + \widehat{j} + \sqrt{2}\widehat{k})}{1\sqrt{1^{2} + 1^{2}\left( \sqrt{2} \right)^{2}}}$
or $cos\theta = \frac{\sqrt{2}}{2} = \frac{1}{\sqrt{2}}$ or $\theta = 45{^\circ}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.