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If vec A =2 hat i+ 3 hat j+ 8 hat k is p...

If `vec A =2 hat i+ 3 hat j+ 8 hat k` is perpendicular to `vec B= 4 hat j -4 hat i+ alpha hat k` , then the value of `alpha`

A

`1/2`

B

`-1/2`

C

1

D

-1

Text Solution

Verified by Experts

The correct Answer is:
B
Here the dot product of two `bot`r vectors is zero i.e.
`(2hati + 3hatj + 8hatk).(4hatj -4hati+ alpha k)=0`
`-8 + 12 + 8alpha=0`
or `8 alpha=-4` pr `alpha=-1/2`
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