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VECTOR ALGEBRA — MATHS STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceMATHSVECTOR ALGEBRA2 Marks
Question
Find $\vec{\text{a}}.\vec{\text{b}}$ when
$\vec{\text{a}}=\hat{\text{j}}-\hat{\text{k}}$ and $\vec{\text{b}}=2\hat{\text{i}}+3\hat{\text{j}}-2\hat{\text{k}}$
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Answer

$\vec{\text{a}}.\vec{\text{b}}=(\hat{\text{j}}-\hat{\text{k}}).(2\hat{\text{i}}+3\hat{\text{j}}-2\hat{\text{k}})$
$=(0\times\hat{\text{i}}+\hat{\text{j}}-\hat{\text{k}})(2\hat{\text{i}}+3\hat{\text{j}}-2\hat{\text{k}})$
$=(0)(2)+(1)(3)+(-1)(-2)$
$=0+3+2$
$\vec{\text{a}}.\vec{\text{b}}=5$

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