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If vecp=(vecbxxvecc)/([(veca,vecb,vecc)]...

If `vecp=(vecbxxvecc)/([(veca,vecb,vecc)]),vecq=(veccxxveca)/([(veca,vecb,vecc)]),vecr=(vecaxxvecb)/([(veca,vecb,vecb)])` where `veca,vecb,vecc` are three non-coplanar vectors, then the value of the expression `(veca+vecb+vecc).(vecp+vecq+vecr)` is

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To solve the problem, we need to evaluate the expression \((\vec{a} + \vec{b} + \vec{c}) \cdot (\vec{p} + \vec{q} + \vec{r})\) where: \[ \vec{p} = \frac{\vec{b} \times \vec{c}}{[\vec{a}, \vec{b}, \vec{c}]}, \quad \vec{q} = \frac{\vec{c} \times \vec{a}}{[\vec{a}, \vec{b}, \vec{c}]}, \quad \vec{r} = \frac{\vec{a} \times \vec{b}}{[\vec{a}, \vec{b}, \vec{c}]} \] Here, \([\vec{a}, \vec{b}, \vec{c}]\) represents the scalar triple product of the vectors \(\vec{a}\), \(\vec{b}\), and \(\vec{c}\). ### Step-by-Step Solution: 1. **Understanding Reciprocal Vectors**: The vectors \(\vec{p}\), \(\vec{q}\), and \(\vec{r}\) are known as reciprocal vectors of \(\vec{a}\), \(\vec{b}\), and \(\vec{c}\). A property of reciprocal vectors states that: \[ \vec{a} \cdot \vec{p} = 1, \quad \vec{b} \cdot \vec{q} = 1, \quad \vec{c} \cdot \vec{r} = 1 \] and the dot products of any vector with the reciprocal of the others are zero: \[ \vec{a} \cdot \vec{q} = 0, \quad \vec{a} \cdot \vec{r} = 0, \quad \vec{b} \cdot \vec{p} = 0, \quad \vec{b} \cdot \vec{r} = 0, \quad \vec{c} \cdot \vec{p} = 0, \quad \vec{c} \cdot \vec{q} = 0 \] 2. **Expanding the Expression**: We need to evaluate: \[ (\vec{a} + \vec{b} + \vec{c}) \cdot (\vec{p} + \vec{q} + \vec{r}) \] This can be expanded as: \[ \vec{a} \cdot \vec{p} + \vec{a} \cdot \vec{q} + \vec{a} \cdot \vec{r} + \vec{b} \cdot \vec{p} + \vec{b} \cdot \vec{q} + \vec{b} \cdot \vec{r} + \vec{c} \cdot \vec{p} + \vec{c} \cdot \vec{q} + \vec{c} \cdot \vec{r} \] 3. **Applying the Properties**: Using the properties of reciprocal vectors: - \(\vec{a} \cdot \vec{p} = 1\) - \(\vec{b} \cdot \vec{q} = 1\) - \(\vec{c} \cdot \vec{r} = 1\) - All other dot products are zero. Thus, the expression simplifies to: \[ 1 + 0 + 0 + 0 + 1 + 0 + 0 + 0 + 1 = 3 \] 4. **Final Result**: Therefore, the value of the expression \((\vec{a} + \vec{b} + \vec{c}) \cdot (\vec{p} + \vec{q} + \vec{r})\) is: \[ \boxed{3} \]

To solve the problem, we need to evaluate the expression \((\vec{a} + \vec{b} + \vec{c}) \cdot (\vec{p} + \vec{q} + \vec{r})\) where: \[ \vec{p} = \frac{\vec{b} \times \vec{c}}{[\vec{a}, \vec{b}, \vec{c}]}, \quad \vec{q} = \frac{\vec{c} \times \vec{a}}{[\vec{a}, \vec{b}, \vec{c}]}, \quad \vec{r} = \frac{\vec{a} \times \vec{b}}{[\vec{a}, \vec{b}, \vec{c}]} \] Here, \([\vec{a}, \vec{b}, \vec{c}]\) represents the scalar triple product of the vectors \(\vec{a}\), \(\vec{b}\), and \(\vec{c}\). ...
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CENGAGE ENGLISH-DIFFERENT PRODUCTS OF VECTORS AND THEIR GEOMETRICAL APPLICATIONS -Exercises MCQ
  1. veca and vecb are two given vectors. On these vectors as adjacent side...

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  2. If veca xx (vec b xx vecc) is perpendicular to (veca xx vecb ) xx vecc...

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  3. If vecp=(vecbxxvecc)/([(veca,vecb,vecc)]),vecq=(veccxxveca)/([(veca,ve...

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  4. a(1), a(2),a(3) in R - {0} and a(1)+ a(2)cos2x+ a(3)sin^(2)x=0 " for ...

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  5. If veca and vecb are two vectors and angle between them is theta , the...

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  6. Let veca and vecb be two non- zero perpendicular vectors. A vector vec...

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  7. If vector vec b=(t a nalpha,-1,2sqrt(sinalpha//2))a n d vec c=(t a na...

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  8. Let vecr be a unit vector satisfying vecr xx veca = vecb, " where " |v...

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  9. If veca and vecb are unequal unit vectors such that (veca - vecb) xx[ ...

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  10. If veca and vecb are two unit vectors perpenicualar to each other and ...

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  11. If vectors veca and vecb are non collinear then veca/(|veca|)+vecb/(|v...

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  12. If veca and vecb are non - zero vectors such that |veca + vecb| = |vec...

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  13. Let veca vecb and vecc be non- zero vectors aned vecV(1) =veca xx (vec...

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  14. Vectors vecA and vecB satisfying the vector equation vecA+ vecB = vec...

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  15. A vector vecd is equally inclined to three vectors veca=hati-hatj+hatk...

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  16. Vectors perpendicular tohati-hatj-hatk and in the plane of hati+hatj+h...

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  17. If the sides vec(AB) of an equilateral triangle ABC lying in the xy-pl...

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  18. Let hata be a unit vector and hatb a non zero vector non parallel to v...

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  19. veca ,vecb and vecc are unimodular and coplanar. A unit vector vecd is...

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  20. If veca + 2 vecb + 3 vecc = vec0 " then " veca xx vecb + vecb xx vecc...

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