Question

A unit vector coplanar with $\overrightarrow{i}+\overrightarrow{j}+2\overrightarrow{k}$ and $\overrightarrow{i}+2\overrightarrow{j}+\overrightarrow{k}$ and perpendicular to $\overrightarrow{i}+\overrightarrow{j}+\overrightarrow{k}$ is

• A. $-\overrightarrow{j}+\overrightarrow{k}$
• B. $\frac{1}{\sqrt2}(-\overrightarrow{j}+\overrightarrow{k})$
• C. $\frac{1}{3}(-\overrightarrow{j}+\overrightarrow{k})$
• D. $\frac{1}{\sqrt3}(-\overrightarrow{j}+\overrightarrow{k})$

Answer 1

Answer: (B)

$\frac{1}{\sqrt2}(-\overrightarrow{j}+\overrightarrow{k})$

Answer 2

The correct option is (B): $\frac{1}{\sqrt2}(-\overrightarrow{j}+\overrightarrow{k})$