Join the Most Relevant JEE Main 2025 Test Series & get 99+ percentile! Join Now
Search any question & find its solution
Question: Answered & Verified by Expert
If $A B C D$ is a parallelogram and the position vectors of $A, B, C$ are $\mathbf{i}+3 \mathbf{j}+5 \mathbf{k}, \mathbf{i}+\mathbf{j}+\mathbf{k}$ and $7 \mathbf{i}+7 \mathbf{j}+7 \mathbf{k}$, then the position vector of $D$ will be
MathematicsVector AlgebraJEE Main
Options:
  • A $7 \mathbf{i}+5 \mathbf{j}+3 \mathbf{k}$
  • B $7 \mathbf{i}+9 \mathbf{j}+11 \mathbf{k}$
  • C $9 \mathbf{i}+11 \mathbf{j}+13 \mathbf{k}$
  • D $8 \mathbf{i}+8 \mathbf{j}+8 \mathbf{k}$
Solution:
2532 Upvotes Verified Answer
The correct answer is: $7 \mathbf{i}+9 \mathbf{j}+11 \mathbf{k}$
Let position vector of $D$ is $x \mathbf{i}+y \mathbf{j}+\mathbf{z} \mathbf{k}$, then $\overrightarrow{A B}=\overrightarrow{D C} \Rightarrow-2 \mathbf{j}-4 \mathbf{k}=(7-x) \mathbf{i}+(7-y) \mathbf{j}+(7-z) \mathbf{k}$ $\Rightarrow x=7, y=9, z=11$.
Hence position vector of $D$ will be $7 \mathbf{i}+9 \mathbf{j}+11 \mathbf{k}$.

Looking for more such questions to practice?

Download the MARKS App - The ultimate prep app for IIT JEE & NEET with chapter-wise PYQs, revision notes, formula sheets, custom tests & much more.