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VECTOR ALGEBRA — Maths STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceMathsVECTOR ALGEBRA2 Marks
Question
Find $\vec{\text{a}}.\vec{\text{b}}$ when
$\vec{\text{a}}=\hat{\text{i}}-2\hat{\text{j}}+\hat{\text{k}}$ and $\vec{\text{b}}=4\hat{\text{i}}-4\hat{\text{j}}+7\hat{\text{k}}$
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Answer

$\vec{\text{a}}.\vec{\text{b}}$
$=(\hat{\text{i}}-2\hat{\text{j}}+\hat{\text{k}}).(4\hat{\text{i}}-4\hat{\text{j}}+7\hat{\text{k}})$
$=(1)(4)+(-2).(-4)+(1)(7)$
$=4+8+7$
$=19$
$\vec{\text{a}}.\vec{\text{b}}=19$

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