JEE Main 2015MathematicsVector AlgebraMediumMCQ

JEE Main 2015 — Vector Algebra Question with Solution

JEE Main 2015 (11 Apr Online)

Question

In a parallelogram ABCD, AB→=a, AD→=b & AC→=c. DB→·AB→ has the value:

Choose an option

Show full solutionCorrect option: D
Correct answer
D12a2-b2+c2

Step-by-step explanation

AB→=a

AD→=b

AC→=b→+a→=c

Squaring both side b→2+a→2-2b→·a→=c2

b2+a2-c2=2b→·a→…1

DB→.AB→=a→-b→·a→

=a→2-a→·b→

=12(a2-b2+c2)

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About this question

This is a previous-year question from JEE Main 2015, 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.