The angle made by the vector A = i + j with x- axis is ....... ^o - Vidyadip

MCQ

The angle made by the vector $A = \hat i + \hat j$ with $x-$ axis is ....... $^o$

A
$90$
✓
$45$
C
$22.5$
D
$30$

✓

Answer

Correct option: B.

$45$

b
(b) $\vec A = \hat i + \hat j$

$⇒$ $|A| = \sqrt {{1^2} + {1^2}} = \sqrt 2 $

$\cos \alpha = \frac{{{A_x}}}{{|A|}} = \frac{1}{{\sqrt 2 }} = \cos 45^\circ $
$⇒$ $\alpha = 45^\circ $

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