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​For two vectors ​​A⃗=2i^+2j^+3k^ and \vec{A}=2 \widehat{i}+2 \widehat{j}+3 \widehat{k} \text { and }A=2i+2j​+3k and ​​​B⃗=5i^+2j^
Question

For two vectors

A=2i^+2j^+3k^ and \vec{A}=2 \widehat{i}+2 \widehat{j}+3 \widehat{k} \text { and }​​

B=5i^+2j^+7k^\vec{B}=5 \widehat{i}+2 \widehat{j}+7 \widehat{k}, find AB\vec{A} \cdot \vec{B}.​

A.

27

B.

37

C.

53

D.

35

Correct option is D

A=2i^+2j^+3k^ Ax=2,Ay=2,Az=3B=5i^+2j^+7k^ Bx=5,By=2,Bz=72. Compute the dot product:AB=(2)(5)+(2)(2)+(3)(7)AB=10+4+21AB=35\begin{aligned}&\vec{A} = 2\hat{i} + 2\hat{j} + 3\hat{k} \implies A_x = 2, \quad A_y = 2, \quad A_z = 3 \\&\vec{B} = 5\hat{i} + 2\hat{j} + 7\hat{k} \implies B_x = 5, \quad B_y = 2, \quad B_z = 7 \\\\&\text{2. Compute the dot product:} \\&\qquad \vec{A} \cdot \vec{B} = (2)(5) + (2)(2) + (3)(7) \\&\qquad \phantom{\vec{A} \cdot \vec{B}} = 10 + 4 + 21 \\&\qquad \phantom{\vec{A} \cdot \vec{B}} = 35\end{aligned}​​

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