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MathematicsVectorDot Product & Its Application ( Projection etc.)Medium2 minPYQ_2021
MathematicsMediumnumerical

Leta=i^+αj^+3k^andb=3i^-αj^+k^. If the area of the parallelogram whose adjacent sides are represented by the vectorsaandbis83square units, thena·bis equal to ___ .

Answer:
2.00
Solution:

a=i^+αj^+3k^

b=3i^-αj^+k^

area of parallelogram =|a×b|=83.

a×b=i^j^k^1α33-α1=i^4α-j^-8+k^-4α

|a×b|=64+32α2=83

2+α2=6α2=4

a·b=3-α2+3=2

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

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