JEE Main 2021MathematicsVector AlgebraEasyMCQ

JEE Main 2021 — Vector Algebra Question with Solution

JEE Main 2021 (25 Jul Shift 2)

Question

If a→=2,b→=5 and a→×b→=8, then a→·b→ is equal to:

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Show full solutionCorrect option: A
Correct answer
A6

Step-by-step explanation

We have, a→=2,b→=5 

and a→×b→=8

Now, a→×b→=a→b→sinθ=8

⇒sinθ=±45

∴ a→·b→=a→b→cosθ

=10.±35=±6

⇒a→·b→=6.

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About this question

This is a previous-year question from JEE Main 2021, 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.