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If (vecaxxvecb)xx(vecbxxvecc)=vecb, wher...

If `(vecaxxvecb)xx(vecbxxvecc)=vecb, where veca,vecb and vecc` are non zero vectors then (A) `veca,vecb and vecc can be coplanar (B) `veca,vecb and vecc` must be coplanar (C) `veca,vecb and vecc cannot be coplanar (D) none of these

A

`veca,vecb and vecv` can be coplanar

B

`veca, vecb and vecc` must be coplanar

C

`veca,vecb and vecc` cannot be coplanar

D

none of these

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The correct Answer is:
To solve the problem, we need to analyze the equation given: \[ (\vec{a} \times \vec{b}) \times (\vec{b} \times \vec{c}) = \vec{b} \] where \(\vec{a}\), \(\vec{b}\), and \(\vec{c}\) are non-zero vectors. We will use the properties of vector products to determine the relationship between these vectors, particularly focusing on their coplanarity. ### Step 1: Apply the Vector Triple Product Identity We start by applying the vector triple product identity, which states that: \[ \vec{x} \times (\vec{y} \times \vec{z}) = (\vec{x} \cdot \vec{z}) \vec{y} - (\vec{x} \cdot \vec{y}) \vec{z} \] In our case, let \(\vec{x} = \vec{a}\), \(\vec{y} = \vec{b}\), and \(\vec{z} = \vec{c}\). Thus, we can rewrite: \[ (\vec{a} \times \vec{b}) \times (\vec{b} \times \vec{c}) = (\vec{a} \cdot \vec{c}) \vec{b} - (\vec{a} \cdot \vec{b}) \vec{c} \] ### Step 2: Set the Equation Now, we set this equal to \(\vec{b}\): \[ (\vec{a} \cdot \vec{c}) \vec{b} - (\vec{a} \cdot \vec{b}) \vec{c} = \vec{b} \] ### Step 3: Rearranging the Equation Rearranging gives us: \[ (\vec{a} \cdot \vec{c}) \vec{b} - \vec{b} = (\vec{a} \cdot \vec{b}) \vec{c} \] This simplifies to: \[ (\vec{a} \cdot \vec{c} - 1) \vec{b} = (\vec{a} \cdot \vec{b}) \vec{c} \] ### Step 4: Analyzing the Coefficients Since \(\vec{b}\) is a non-zero vector, we can analyze the coefficients: 1. If \(\vec{a} \cdot \vec{c} - 1 = 0\), then \(\vec{a} \cdot \vec{c} = 1\). 2. If \(\vec{a} \cdot \vec{b} \neq 0\), then \(\vec{c}\) must be a non-zero vector. ### Step 5: Coplanarity Condition For vectors \(\vec{a}\), \(\vec{b}\), and \(\vec{c}\) to be coplanar, the scalar triple product \(\vec{a} \cdot (\vec{b} \times \vec{c})\) must be zero. However, we have shown that: \[ \vec{a} \cdot (\vec{b} \times \vec{c}) = 1 \] This indicates that the vectors are not coplanar. ### Conclusion Based on the analysis, we conclude that: **The correct answer is (C) \(\vec{a}\), \(\vec{b}\), and \(\vec{c}\) cannot be coplanar.** ---

To solve the problem, we need to analyze the equation given: \[ (\vec{a} \times \vec{b}) \times (\vec{b} \times \vec{c}) = \vec{b} \] where \(\vec{a}\), \(\vec{b}\), and \(\vec{c}\) are non-zero vectors. We will use the properties of vector products to determine the relationship between these vectors, particularly focusing on their coplanarity. ...
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CENGAGE ENGLISH-DIFFERENT PRODUCTS OF VECTORS AND THEIR GEOMETRICAL APPLICATIONS -Exercises MCQ
  1. If veca .vecb =beta and veca xx vecb = vecc ," then " vecb is

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  2. If a(vecalpha xx vecbeta)xx(vecbetaxxvecgamma)+c(vecgammaxxvecalpha)=0...

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  3. If (vecaxxvecb)xx(vecbxxvecc)=vecb, where veca,vecb and vecc are non z...

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  4. If vecr.veca=vecr.vecb=vecr.vecc=1/2 for some non zero vector vecr and...

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  5. A vector of magnitude 10 along the normal to the curve 3x^2+8x y+2y^...

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  6. If veca and vecb are two unit vectors inclined at an angle pi/3 then {...

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  7. If veca and vecb are othogonal unit vectors, then for a vector vecr no...

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  8. If veca+vecb ,vecc are any three non- coplanar vectors then the equa...

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  9. Sholve the simultasneous vector equations for vecx and vecy: vecx+vecc...

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  10. The condition for equations vecrxxveca = vecb and vecr xx vecc = vecd ...

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  11. If veca=2hati+3hatj+hatk, vecb=hati-2hatj+hatk and vecc=-3hati+hatj+2h...

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  12. If veca=2hati + hatj+ hatk, vecb= hati+ 2hatj + 2hatk,vecc = hati+ hat...

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  13. Let (veca (x) = (sin x) hati+ (cos x) hatj and vecb(x) = (cos 2x) hati...

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  14. For any vectors veca and vecb, (veca xx hati) + (vecb xx hati) + ( vec...

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  15. If veca,vecb and vecc are three non coplanar vectors and vecr is any v...

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  16. If vecP = (vecbxxvecc)/([vecavecbvecc]).vecq=(veccxxveca)/([veca vecb ...

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  17. A (veca), B (vecb) and C (vecc) are the vertices of triangle ABC and R...

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  18. If veca , vecb and vecc are non- coplanar vectors and veca xx vecc is ...

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  19. If V be the volume of a tetrahedron and V ' be the volume of another...

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  20. [(veca xxvecb)xx(vecb xx vecc) (vecb xxvecc) xx (vecc xxveca)...

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