JEE Main 2021MathematicsVector AlgebraEasyMCQ

JEE Main 2021 — Vector Algebra Question with Solution

JEE Main 2021 (18 Mar Shift 2)

Question

Let a→ and b→ be two non-zero vectors perpendicular to each other and |a→|=|b→|, If |a→×b→|=|a→|, then the angle between the vectors
(a→+b→+(a→×b→)) and a→ is equal to :

Choose an option

Show full solutionCorrect option: B
Correct answer
Bcos-113

Step-by-step explanation

|a→|=|b→|,|a→×b→|=|a→|,a→⊥b→

|a→×b→|=|a→|⇒|a→||b→|sin90°=|a→|⇒|b→|=1=|a→|

a→ and b→ are mutually perpendicular unit vectors.

Let a→=i^,b→=j^⇒a→×b→=k^

cosθ=(i^+j^+k^)i^31=13⇒θ=cos-113

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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.