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If the points with position vectors 60 h...

If the points with position vectors `60 hat i+2 hat j , 40 hat i-8 hat ja n da hat i-52 hat j` are collinear, find the value of `adot`

A

`a=- 48`

B

`a=40`

C

`a=20`

D

None of the these

Text Solution

Verified by Experts

The correct Answer is:
A
Three points A ,B,C are collinear if ` vec(AB) =- 20 hat(i) - 11hat(j)`
` " and " vec(AC) =(a -60)hat(i) -55 hat(j) " tnen " vec(AB) ||vec(AC )`
`rArr (a-60)/(-20) =(-55)/(-11) rArr a =- 40`
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