The position vectors of vertices of a `Delta ABC` are `4hat(i)-2hat(j), hat(i)-3hat(k)` and `-hat(i)+5hat(j)+hat(k)` respectively, then `angle ABC` is equal to
A. `pi/6`
B. `pi/4`
C. `pi/3`
D. `pi/2`

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1 Answers

Correct Answer - D
Here, `AB=-3 hati+6hatj-3hatk`
`BC = -2 hati+hatj+4hatk`
and `AB*BC=6+6-12=0`
`rArr" "/_ABC=pi/2`

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