If \(\vec{a}=\hat{i}+\hat{j}+\hat{k}\), \(\vec{b}=2\hat{i}-\hat{j}+3\hat{k}\) and \(\vec{c}=\hat{i}-2\hat{j}+\hat{k}\) then a vector of magnitude \(\sqrt{22}\) which is parallel to \(2\vec{a}-\vec{b}+3\vec{c}\) is
Step-by-step Solution:
Correct Answer: A ($3\hat{i} - 3\hat{j} + 2\hat{k}$)
The solution involves two main steps: first, finding the direction of the required vector, and second, scaling it to the correct magnitude.
A vector that is parallel to $2\vec{a} - \vec{b} + 3\vec{c}$ will have the same direction. Let's first calculate this resultant vector, which we'll call $\vec{v}_{dir}$.
Given vectors:
$\vec{v}_{dir} = 2\vec{a} - \vec{b} + 3\vec{c}$
$\vec{v}_{dir} = 2(\hat{i} + \hat{j} + \hat{k}) - (2\hat{i} - \hat{j} + 3\hat{k}) + 3(\hat{i} - 2\hat{j} + \hat{k})$
$\vec{v}_{dir} = (2\hat{i} + 2\hat{j} + 2\hat{k}) - (2\hat{i} - \hat{j} + 3\hat{k}) + (3\hat{i} - 6\hat{j} + 3\hat{k})$
Now, combine the components:
$\vec{v}_{dir} = (2 - 2 + 3)\hat{i} + (2 - (-1) - 6)\hat{j} + (2 - 3 + 3)\hat{k}$
$\vec{v}_{dir} = 3\hat{i} - 3\hat{j} + 2\hat{k}$
This is the direction of the vector we are looking for.
We need a vector with a magnitude of $\sqrt{22}$. Let's first find the magnitude of our direction vector, $|\vec{v}_{dir}|$.
$|\vec{v}_{dir}| = \sqrt{(3)^2 + (-3)^2 + (2)^2}$
$|\vec{v}_{dir}| = \sqrt{9 + 9 + 4} = \sqrt{22}$
The magnitude of our direction vector is already $\sqrt{22}$, which is the required magnitude. Therefore, the vector we are looking for is exactly $\vec{v}_{dir}$.
Required Vector = $3\hat{i} - 3\hat{j} + 2\hat{k}$