Question

The angle between the two vectors - 2i +3j + k and i + 2j - 4k is:

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Answer 1

Answer:

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Correct option is

B

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The angle between the two vectors A and B is 

cosθ=∣∣∣∣AB∣∣∣∣A⋅B

 A⋅B =  (−2i+3j+k)⋅(i+2j−4k)=−2+6−4=0

A=(2)2+(3)2+(1)2=14

B=(1)2+(2)2+(4)2=21