Question

The cross product of vectors A = $(\hat{i}+\hat{j})$ and B =$(\hat{i}+\hat{k})$ in

• A. $\hat{i}+\hat{j}+\hat{k}$
• B. $\hat{i}-\hat{j}+\hat{k}$
• C. $\hat{i}+\hat{j}-\hat{k}$
• D. $\hat{i}-\hat{j}-\hat{k}$

Answer 1

The correct option is D $\hat{i}-\hat{j}-\hat{k}$

$A\times B=(\hat{i}+\hat{j})\times (\hat{i}+\hat{k})=\hat{i}\times \hat{i}+\hat{i}\times \hat{k}+\hat{j}\times \hat{i}+\hat{j}\times \hat{k}$
$=0-\hat{j}-\hat{k}+\hat{i}$ which is choice (d)