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If veca*vecb=-|veca|*|vecb|, then theta=...

If `veca*vecb=-|veca|*|vecb|`, then `theta=`,

A

`pi`

B

`pi/2`

C

`(3pi)/2`

D

None of these.

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MODERN PUBLICATION-VECTORS-Exercise
  1. If veca=2hati+3hatj-5hatk and vecb=hati+hatj-hatk, then veca*vecb is :

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  2. Magnitude of the vector vec(PQ), joining the points P(2,3,0) and Q(1,-...

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  3. If veca*vecb=-|veca|*|vecb|, then theta=,

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  4. If veca is a non-zero vector of magnitude 'a' and 'lambda' is a non-ze...

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  5. The value of hati*(hatjxxhatk)+hatj*(hatixxhatk)+hatk*(hatixxhatj) is ...

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  6. The projection of veca=2hati-hatj+hatk on vecb=hati-2hatj+hatk is equa...

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  7. If |veca*vecb|=|vecaxxvecb|, then the angle between veca and vecb is :

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  8. Let veca=hati-2hatj+3hatk. If vecb be a vector such that : veca*vecb=|...

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  9. If veca,vecb,vecc are three non-zero vectors such that each one of the...

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  10. If veca=hati+2hatj+2hatk, |vecb|=5 and the angle between veca and vceb...

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  11. If veca*vecb=0 and veca+vecb makes an angle of 60^@ with veca, then :

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  12. The area of the parallelogram whose adjacent sides are hati+hatk and 2...

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  13. If the projection of vecb on veca is twice the projection of veca on v...

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  14. If (vecaxxvecb)^2+(veca*vecb)^2=144 and |veca|=4, then |vecb|=

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  15. The non-zero vectors veca,vecb and vecc are related by veca=8vecb and ...

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  16. The edges of a parallelopiped are of unit length and are parallel to ...

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  17. If a, b, c and d are the unit vectors such that (atimesb)*(ctimesd)=1 ...

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  18. If vecu, vecv, vecw are non -coplanar vectors and p,q, are real numbe...

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  19. Let veca =hatj-hatk and vecc =hati-hatj-hatk. Then the vector b satisf...

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  20. If the vectors veca=hati-hatj+2hatk.vecb=2hati+4hatj+hatk and vec c=la...

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