Question

A vector is represented by $3\hat{i}+\hat{j}+2\hat{k}$. Its length in $XY$ plane is

• A. $2$
• B. $\sqrt{14}$
• C. $\sqrt{10}$
• D. $\sqrt{5}$

Answer 1

The correct option is C $\sqrt{10}$

Let $\overrightarrow{R}=3\hat{i}+\hat{j}+2\hat{k}$
So, length in $XY$ plane is given as
$\sqrt{R_x^2+R_y^2}=\sqrt{3^2+1^2}=\sqrt{10}$