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Find the angle between two lines whose d...

Find the angle between two lines whose direction ratios are proportional to `1,1,2a n d(sqrt(3)-1),(-sqrt(3)-1),4` .

A

`45^(@)`

B

`30^(@)`

C

`60^(@)`

D

`90^(@)`

Text Solution

Verified by Experts

The correct Answer is:
A
Let `theta` be the angle between the given lines. Then
`cos theta=(1xx(sqrt(3)-1)+1xx(-sqrt(3)-1)+2xx4)/(sqrt(1+1+4)sqrt((sqrt(3)-1)^(2)+(-sqrt(3)-1)^(2)+4))=1/(sqrt(2))`
`implies theta=45^(@)`
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  12. If vecr is a vector of magnitude 21 and has direction ratios proporti...

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