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Vector — JEE physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 ScienceJEE physicsVector1 Mark
MCQ
The angle between the vectors $(\hat{i} \quad \hat{j})$ and $(\hat{j} \quad \hat{k})$ is
  • A
    $30^{\circ}$
  • B
    $45^{\circ}$
  • ✓
    $60^{\circ}$
  • D
    $90^{\circ}$
✓

Answer

Correct option: C.
$60^{\circ}$
(c)$\begin{aligned}& (\hat{i}+\hat{j}) \cdot(\hat{j}+\hat{k})=0+0+1+0=1 \\& \cos \theta=\frac{\vec{A} \cdot \vec{B}}{|\vec{A}||\vec{B}|}=\frac{1}{\sqrt{2} \times \sqrt{2}=\frac{1}{2} \therefore \theta=60^{\circ}\end{aligned}$

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