Answer
$7 \sqrt 3$
Work Step by Step
The formula to calculate the distance for two vectors is given by:
$d=\dfrac{|u \times v|}{|v|}$
Thus, we have $u \times v=\lt -28,-56,28\gt $
and $|u \times v|=\sqrt{(-28)^2+(-56)^2+(28)^2}=28 \sqrt {6}$
Now, $d=\dfrac{|u \times v|}{|v|}=\dfrac{28 \sqrt {6}}{ \sqrt {(4)^2+(0)^2+(4)^2}}=\dfrac{28 \sqrt {6}}{ 4 \sqrt {2}}=7 \sqrt 3$
