Question

A vector =2i-j+k,B vector=i-j find theta?
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Answer 1

Answer:

Let a=i^+j^+k^ and b=2i^−2j^+2k^ and angle between them be θ

Then, cosθ=∣a∣∣b∣a⋅b

=(1)2+(1)2+(1)2(2)2+(−2)2+(2)2(i^+j^+k^)⋅(2i^−2j^+2k^)

=3122−2+2=62=31

⇒θ=cos−1(31)