Question
If $\hat{\text{a}}, \hat{\text{b}}$ and $\hat{\text{c}}$are mutually perpendicular unit vectors, then find the value of $|\hat{2\text{a}} + \hat{\text{b}} + \hat{\text{c}}|.$

Answer

$|2\hat{\text{a}} + \hat{\text{b}} + \hat{\text{c}}|^{2} = (2\hat{\text{a}})^{2} + (\hat{\text{b}})^{2} + (\hat{\text{c}})^{2} +2(2\hat{\text{a}}. \hat{\text{b}} + \hat{\text{b}}. \hat{\text{c}} + \hat{\text{c}}. 2\hat{\text{a}})$
$\therefore|2\hat{\text{a}} + \hat{\text{b}} + \hat{\text{c}}| = \sqrt{6}$

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