Question

Angle between two vectors $(\hat{i}+\hat{j})$ and $(\hat{i}-\hat{j})$ is

• A. $30^{\circ }$
• B. $60^{\circ }$
• C. $45^{\circ }$
• D. $90^{\circ }$

Answer 1

Answer: (D)

$\cos \theta =\frac{(\hat{i}+\hat{j})\cdot (\hat{i}-\hat{j})}{|\hat{i}+\hat{j}\Vert \hat{i}-\hat{j}|}=\frac{1-1}{\sqrt{2}\cdot \sqrt{2}}=0$
$\Rightarrow \theta =90^{\circ }$