Question

lf $0.5\overline{i}+0.8\overline{j}+C\overline{k}$ is a unit vector, then $C$ is:

• A. $\sqrt{89}$
• B. 0.2
• C. 0.3
• D. $\sqrt{0.11}$

Answer 1

The correct option is D $\sqrt{0.11}$

Given vector is a unit vector so its magnitude will be 1 therefore we have above equation by the formula of "magnitude of a vector"

$1=\sqrt{{0.5}^2+{0.8}^2+C^2}$

$1^2={0.5}^2+{0.8}^2+C^2$

$C=\sqrt{0.11}$