Answer
$\dfrac{9}{\sqrt {41}}$
Work Step by Step
The formula to calculate the distance for two vectors is given by:
$d=\dfrac{|u \cdot v|}{|v|}$
Thus, we have $u \cdot v=7(1)+(-2)(2)+1(6)=9$
and $|u \times v|=|9|=9$
Now, $d=\dfrac{|u \cdot v|}{|v|}=\dfrac{9}{ \sqrt {(1)^2+(2)^2+(6)^2}}=\dfrac{9}{\sqrt {41}}$
