Answer
$\dfrac{9}{\sqrt {41}}$
Work Step by Step
The distance formula for two vectors can be calculated as:
$d=\dfrac{|p \cdot q|}{|q|}$
Now, $p \cdot q=7(1)+(-2)(2)+1(6)=9$
and $|p \times q|=|9|=9$
Thus, $d=\dfrac{9}{ \sqrt {(1)^2+(2)^2+(6)^2}}=\dfrac{9}{ \sqrt {1+4+36}}$
or, $=\dfrac{9}{\sqrt {41}}$
