JEE Main 2021PhysicsMathematics in PhysicsMediumMCQ

JEE Main 2021 — Mathematics in Physics Question with Solution

JEE Main 2021 (20 Jul Shift 2)

Question

Two vectors P→ and Q→ have equal magnitudes. If the magnitude of P→+Q→ is n times the magnitude of P→-Q→, then angle between P→ and Q→ is

Choose an option

Show full solutionCorrect option: D
Correct answer
Dcos-1n2-1n2+1

Step-by-step explanation

|P→|=|Q→|=x  …i

|P→+Q→|=n|P→-Q→|

P2+Q2+2PQcosθ=n2P2+Q2-2PQcosθ

Using (i) in above equation,

cosθ=n2-11+n2

θ=cos-1n2-1n2+1

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About this question

This is a previous-year question from JEE Main 2021, covering the Mathematics in Physics chapter of Physics. 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.