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MathematicsVectorDot Product & Its Application ( Projection etc.)Easy2 minPYQ_2021
MathematicsEasysingle choice

A vectorahas components3pand1with respect to a rectangular cartesian system. This system is rotated through a certain angle about the origin in the counter clockwise sense. If, with respect to new system,ahas componentsp+1and10,then a value ofpis equal to:

Question diagram: A vector a → has components 3 p and 1 with respect to a rect

Options:

Answer:
D
Solution:

aOld=3pi^+j^

aNew=(p+1)i^+10j^

aOld=aNew

9p2+1=p2+2p+1+10

8p2-2p-10=0

4p2-p-5=0

(4p-5)(p+1)=0p=54,-1

Stream:JEESubject:MathematicsTopic:VectorSubtopic:Dot Product & Its Application ( Projection etc.)
2mℹ️ Source: PYQ_2021

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