JEE Main 2026 — Vector Algebra Question with Solution
JEE Main 2026 (28 January Shift 1)
Question
For three unit vectors satisfying and , the positive value of k is
Choose an option
Show full solutionCorrect option: C
Correct answer
C5
Step-by-step explanation
Expanding with unit vectors gives .
So .
For the symmetric case where vectors are equally spaced (e.g., on a circle at 120° intervals), we have .
Expanding gives .
Substituting the symmetric values: , which simplifies to .
Factoring: , giving as the positive solution.
So .
For the symmetric case where vectors are equally spaced (e.g., on a circle at 120° intervals), we have .
Expanding gives .
Substituting the symmetric values: , which simplifies to .
Factoring: , giving as the positive solution.
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This is a previous-year question from JEE Main 2026, covering the Vector Algebra chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.