Question

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

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

Answer 1

Answer: (B)

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