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A vector vecr is equally inclined with t...

A vector `vecr` is equally inclined with the coordinates axes. If the tip of `vecr` is in the positive octant and `|vecr|=6`, then `vecr` is

A

`2sqrt(3)(hati-hatj+hatk)`

B

`2sqrt(3)(-hati+hatj+hatk)`

C

`2sqrt(3)(hati+hatj-hatk)`

D

`2sqrt(3)(hati+hatj+hatk)`

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The correct Answer is:
To solve the problem, we need to find the vector \( \vec{r} \) that is equally inclined with the coordinate axes and has a magnitude of 6. ### Step-by-step Solution: 1. **Understanding the Inclination**: Since the vector \( \vec{r} \) is equally inclined to the coordinate axes, the direction cosines of the vector with respect to the x, y, and z axes are equal. Let's denote these direction cosines as \( l \), \( m \), and \( n \). Therefore, we have: \[ l = m = n \] 2. **Using the Property of Direction Cosines**: The sum of the squares of the direction cosines is equal to 1: \[ l^2 + m^2 + n^2 = 1 \] Substituting \( l = m = n \) into the equation gives: \[ 3l^2 = 1 \implies l^2 = \frac{1}{3} \implies l = \frac{1}{\sqrt{3}} \] 3. **Constructing the Vector**: The vector \( \vec{r} \) can be expressed in terms of its components along the x, y, and z axes: \[ \vec{r} = l \hat{i} + m \hat{j} + n \hat{k} = l (\hat{i} + \hat{j} + \hat{k}) = \frac{1}{\sqrt{3}} (\hat{i} + \hat{j} + \hat{k}) \] 4. **Finding the Magnitude**: We know that the magnitude of the vector \( \vec{r} \) is given as 6: \[ |\vec{r}| = 6 \] Therefore, we can express \( \vec{r} \) as: \[ \vec{r} = 6 \cdot \frac{1}{\sqrt{3}} (\hat{i} + \hat{j} + \hat{k}) = 2\sqrt{3} (\hat{i} + \hat{j} + \hat{k}) \] 5. **Final Expression of the Vector**: Thus, the vector \( \vec{r} \) is: \[ \vec{r} = 2\sqrt{3} \hat{i} + 2\sqrt{3} \hat{j} + 2\sqrt{3} \hat{k} \] ### Conclusion: The vector \( \vec{r} \) that is equally inclined with the coordinate axes and has a magnitude of 6 is: \[ \vec{r} = 2\sqrt{3} (\hat{i} + \hat{j} + \hat{k}) \]

To solve the problem, we need to find the vector \( \vec{r} \) that is equally inclined with the coordinate axes and has a magnitude of 6. ### Step-by-step Solution: 1. **Understanding the Inclination**: Since the vector \( \vec{r} \) is equally inclined to the coordinate axes, the direction cosines of the vector with respect to the x, y, and z axes are equal. Let's denote these direction cosines as \( l \), \( m \), and \( n \). Therefore, we have: \[ l = m = n ...
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OBJECTIVE RD SHARMA-THREE DIMENSIONAL COORDINATE SYSTEM -Exercise
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  8. A vector vecr is equally inclined with the coordinates axes. If the ti...

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  12. The foot of the perpendicular drawn from a point with position vector ...

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  14. Let l1,m1,n1; l2,m2,n2 and l3,m3,n3 be the direction cosines of three ...

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