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If |A|=2,|B|=5 and |AxxB|=8. Angle betw...

If `|A|=2,|B|=5` and `|AxxB|=8.` Angle between A and B is acute, then `(A.B)` is

A

6

B

3

C

4

D

7

Text Solution

Verified by Experts

The correct Answer is:
A
(a) We have `AxxB =AB=sintheta`
8 =(5) (2) `sintheta`
`sin theta=4//5 or cos theta=3//5`
`A.B =AB cos theta =(5)(2) (3//5) =6`
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