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Question: Answered & Verified by Expert
The position vectors of $A$ and $B$ are $2 \mathbf{i}-9 \mathbf{j}-4 \mathbf{k}$ and $6 \mathbf{i}-3 \mathbf{j}+8 \mathbf{k}$ respectively, then the magnitude of $\overrightarrow{A B}$ is
MathematicsVector AlgebraJEE Main
Options:
  • A 11
  • B 12
  • C 13
  • D 14
Solution:
2779 Upvotes Verified Answer
The correct answer is: 14
$\begin{aligned}
& \overrightarrow{A B}=(6-2) \mathbf{i}+(-3+9) \mathbf{j}+(8+4) \mathbf{k}=4 \mathbf{i}+6 \mathbf{j}+12 \mathbf{k} \\
& |\overrightarrow{A B}|=\sqrt{16+36+144}=14
\end{aligned}$

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