Q. If $0.5\widehat{i} + 0.8\widehat{j} + c\widehat{k}$ is a unit vector, then the value of $c$ is
A) $\sqrt{0.11}$
B) $\sqrt{0.22}$
C) $\sqrt{0.33}$
D) $\sqrt{0.89}$
Explanation
(a) $(0.5)^{2} + (0.8)^{2} + c^{2} = 1$
0.25+0.64+$c^{2} = 1$
or $c^{2} = 1 - 0.25 - 0.64 = 0.11$
or $c = \sqrt{0.11}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.