Chapter 11 - Section 11.5 - Lines and Planes in Space - Exercises - Page 631: 39

$3$

The formula to calculate the distance for two vectors is given by: $d=\dfrac{|u \cdot v|}{|v|}$ Thus, we have $u \cdot v=1(3)+2(5)+2(-2)=9 $ and $|u \times v|=|9|=9$ Now, $d=\dfrac{|u \cdot v|}{|v|}=\dfrac{9}{ \sqrt {(1)^2+(2)^2+(2)^2}}=\dfrac{9}{ 3}=3$