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If the vectors veca and vecb are perpend...

If the vectors `veca` and `vecb` are perpendicular to each other then a vector `vecv` in terms of `veca` and `vecb` satisfying the equations `vecv.veca=0, vecv.vecb=1` and `[(vecv, veca, vecb)]=1` is

A

`(vecb)/(|vecb|^(2))+(vecaxxvecb)/(|vecaxxvecb|^(2))`

B

`(vecb)/(|vecb|)+(vecaxxvecb)/(|vecaxxvecb|^(2))`

C

`(vecb)/(|vecb|^(2))+(vecaxxvecb)/(|vecaxxvecb|)`

D

none of these

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To solve the problem, we need to find the vector \(\vec{v}\) in terms of the vectors \(\vec{a}\) and \(\vec{b}\) given the conditions that \(\vec{v} \cdot \vec{a} = 0\), \(\vec{v} \cdot \vec{b} = 1\), and \([\vec{v}, \vec{a}, \vec{b}] = 1\). ### Step 1: Understand the Conditions Since \(\vec{a}\) and \(\vec{b}\) are perpendicular, we can use the properties of dot products and cross products. The first condition, \(\vec{v} \cdot \vec{a} = 0\), indicates that \(\vec{v}\) is orthogonal to \(\vec{a}\). The second condition, \(\vec{v} \cdot \vec{b} = 1\), indicates that \(\vec{v}\) has a component in the direction of \(\vec{b}\). ### Step 2: Express \(\vec{v}\) in terms of \(\vec{a}\) and \(\vec{b}\) We can express \(\vec{v}\) as a linear combination of \(\vec{a}\) and \(\vec{b}\) and a term that ensures it is orthogonal to \(\vec{a}\): \[ \vec{v} = k \vec{b} + m (\vec{a} \times \vec{b}) \] where \(k\) and \(m\) are scalars to be determined. ### Step 3: Apply the First Condition Using the first condition \(\vec{v} \cdot \vec{a} = 0\): \[ (k \vec{b} + m (\vec{a} \times \vec{b})) \cdot \vec{a} = 0 \] Since \(\vec{a} \cdot \vec{a} = |\vec{a}|^2\) and \(\vec{b} \cdot \vec{a} = 0\) (because they are perpendicular), we have: \[ m (\vec{a} \times \vec{b}) \cdot \vec{a} = 0 \] This condition is automatically satisfied because the cross product \(\vec{a} \times \vec{b}\) is perpendicular to both \(\vec{a}\) and \(\vec{b}\). ### Step 4: Apply the Second Condition Using the second condition \(\vec{v} \cdot \vec{b} = 1\): \[ (k \vec{b} + m (\vec{a} \times \vec{b})) \cdot \vec{b} = 1 \] This simplifies to: \[ k |\vec{b}|^2 = 1 \implies k = \frac{1}{|\vec{b}|^2} \] ### Step 5: Use the Third Condition The third condition \([\vec{v}, \vec{a}, \vec{b}] = 1\) represents the scalar triple product, which can be expressed as: \[ [\vec{v}, \vec{a}, \vec{b}] = \vec{v} \cdot (\vec{a} \times \vec{b}) \] Substituting \(\vec{v} = \frac{1}{|\vec{b}|^2} \vec{b} + m (\vec{a} \times \vec{b})\): \[ \left(\frac{1}{|\vec{b}|^2} \vec{b} + m (\vec{a} \times \vec{b})\right) \cdot (\vec{a} \times \vec{b}) = 1 \] The first term evaluates to zero because \(\vec{b} \cdot (\vec{a} \times \vec{b}) = 0\). Thus, we have: \[ m \cdot |\vec{a} \times \vec{b}| = 1 \implies m = \frac{1}{|\vec{a} \times \vec{b}|} \] ### Final Expression for \(\vec{v}\) Combining everything, we have: \[ \vec{v} = \frac{1}{|\vec{b}|^2} \vec{b} + \frac{1}{|\vec{a} \times \vec{b}|} (\vec{a} \times \vec{b}) \]

To solve the problem, we need to find the vector \(\vec{v}\) in terms of the vectors \(\vec{a}\) and \(\vec{b}\) given the conditions that \(\vec{v} \cdot \vec{a} = 0\), \(\vec{v} \cdot \vec{b} = 1\), and \([\vec{v}, \vec{a}, \vec{b}] = 1\). ### Step 1: Understand the Conditions Since \(\vec{a}\) and \(\vec{b}\) are perpendicular, we can use the properties of dot products and cross products. The first condition, \(\vec{v} \cdot \vec{a} = 0\), indicates that \(\vec{v}\) is orthogonal to \(\vec{a}\). The second condition, \(\vec{v} \cdot \vec{b} = 1\), indicates that \(\vec{v}\) has a component in the direction of \(\vec{b}\). ### Step 2: Express \(\vec{v}\) in terms of \(\vec{a}\) and \(\vec{b}\) We can express \(\vec{v}\) as a linear combination of \(\vec{a}\) and \(\vec{b}\) and a term that ensures it is orthogonal to \(\vec{a}\): \[ ...
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OBJECTIVE RD SHARMA-SCALAR AND VECTOR PRODUCTS OF THREE VECTORS -Section I - Solved Mcqs
  1. If vecu and vecv be unit vectors. If vecw is a vector such that vecw+(...

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  2. If veca, vecb, vecc be three vectors of magnitude sqrt(3),1,2 such tha...

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  3. If the vectors veca and vecb are perpendicular to each other then a ve...

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  4. The value of a so that the volume of the paralelopiped formed by hati+...

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  5. Let veca, vecb and vecc be three vectors having magnitudes 1,1 and 2 r...

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  6. If veca, vecb, vecc are vectors such that |vecb|=|vecc| then {(veca+ve...

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  7. If the magnitude of the moment about the pont hatj+hatk of a force hat...

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  8. If the volume of the parallelopiped formed by the vectors veca, vecb, ...

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  9. If |veca|=5, |vecb|=3, |vecc|=4 and veca is perpendicular to vecb and ...

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  10. If veca, vecb, vecc, vecd are coplanar vectors, then (vecaxxvecb)xx(ve...

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  11. {veca.(vecbxxhati)}hati+{veca.(vecbxxhatj)}hatj+{veca.(vecbxxhatk)}hat...

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  12. The unit vector which is orhtogonal to the vector 3hati+2hatj+6hatk an...

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  13. Let veca,vecb and vecc be non-zero vectors such that no two are collin...

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  14. Let vecp,vecq, vecr be three mutually perpendicular vectors of the sam...

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  15. If veca and vecb are vectors in space given by veca=(hati-2hatj)/(sqrt...

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  16. Two adjacent sides of a parallelogram ABCD are given by vec(AB)=2hati+...

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  17. Let veca=hatj-hatk and vecc=hati-hatj-hatk. Then the vector vecb satis...

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  18. The vector (s) which is (are) coplanar with vectors hati+hatj+2hatk an...

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  19. Let veca=-hati-hatk, vecb=-hati+hatj and vecc=hati+2hatj+3hatk be th...

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  20. If veca=1/(sqrt(10))(3hati+hatk),vecb=1/7(2hati+3hatj-6hatk), then the...

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