Question

The angle made by the vector $A=\hat{i}+\hat{j}$ with $x-$axis is

• A. ${90}^o$
• B. ${45}^o$
• C. ${22.5}^o$
• D. ${30}^o$

Answer 1

Answer: (B)

${45}^o$

$\overrightarrow{A}=\hat{i}+\hat{j}\Rightarrow |A|=\sqrt{1^2+1^2}=\sqrt{2}$
$\cos \alpha =\frac{A_x}{|A|}=\frac{1}{\sqrt{2}}=\cos {45}^o\therefore \alpha ={45}^o$