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`vec(a),vec(b)` and `vec( c )` are unit vectors `vec(a)xx(vec(b)xx vec( c ))=(vec(b))/(2)`. The vector `vec(a)` makes the angle ………, …… with `vec(b)` and `vec( c )` respectively.

A

`40^(@),80^(@)`

B

`45^(@),45^(@)`

C

`30^(@),60^(@)`

D

`90^(@),60^(@)`

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The correct Answer is:
D
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KUMAR PRAKASHAN-VECTOR ALGEBRA -Solutions of NCERT Exemplar Problems (Multiple Choice Questions (MCQs) )
  1. If vec(a)=2hati+hatj+x hatk and vec(b)=hati+hatj-hatk then the minimum...

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  2. If vec(a).hati=4 then (vec(a)xx hatj).(2hatj-3hatk)= ………..

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  3. vec(a),vec(b) and vec( c ) are unit vectors vec(a)xx(vec(b)xx vec( c )...

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  4. If vec(u)=hati xx(vec(a)xx hati)+hatj xx(vec(a)xx hatj)+hatk xx(vec(a)...

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  5. For the vectors vec(x) and vec(y),vec(x)+vec(y)=vec(a),vec(x)xx vec(y)...

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  6. Vector vec(a)=hati-hatj,vec(b)=hati+hatj+hatk. The vector vec( c ) is ...

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  7. The vectors vec(a) and vec(b) are not perpendicular. The vectors vec( ...

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  8. vec(a)=hatj-hatk and vec( c )=hati-hatj-hatk. The vector vec(b) is suc...

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  9. For any vector vec(a),(vec(a)xx vec(i))^(2)+(vec(a)xx hatj)^(2)+(vec(a...

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  10. vec(a),vec(b) and vec( c ) are three vector vec(a)ne0 and |vec(a)|=|ve...

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  11. For any vecotr vec(a), The value of hati xx(vec(a)xx hati)+j xx(vec(a)...

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  12. If (a(1),1,1),(1,a(2),1) and (1,1,a(3)) are coplaner (where a(i)ge1,i=...

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  13. If bar(x)=(1,-1,0),bar(y)=(0,1,3) and bar(z)=(2,1,1) then bar(x)xx (ba...

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  14. If [vec(a)xx vec(b),vec(b)xx vec( c ),vec( c )xx vec(a)]=lambda[vec(a)...

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  15. The volume of a parallelepiped with edges vec(OA)=(3,1.4),vec(OB)=(1,2...

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  16. Let vec(a),vec(b) and vec( c ) are three unit vectors such that vec(a)...

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  17. If |bar(a)|=1 and bar(a)xx bar(b)=(1,2,3) then bar(a)xx[bar(a)xx(bar(a...

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  18. If bar(x)xx(bar(y)xx bar(z))=(bar(x)xx bar(y))xx bar(z) then bar(y)xx(...

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  19. Let vec(a)=2hati+hatj-2hatk and vec(b)=hati+hatj. Let the vector vec( ...

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  20. If the unit bar(a),bar(b) and bar( c ) are coplanar then …………..

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