Question

Find the direction ratios of the vector $\overrightarrow{a}=\hat{i}+\hat{j}-2\hat{k}$.

• A. $1,1-2$
• B. $-1,1,-2$
• C. $1,1,2$
• D. None of these

Answer 1

The correct option is A $1,1-2$

Given $\overrightarrow{a}=\overrightarrow{i}+\overrightarrow{j}-\overrightarrow{2}k$

Direction ratios are $a=1,b=1,c=-2$

Magnitude of $\overrightarrow{a}=\sqrt{1^2+1^2+(-2{)}^2}$

$|a|=\sqrt{1+1+4}=\sqrt{6}$

The direction cosines of $\overrightarrow{a}$ are $1,1,-2$