## Thomas' Calculus 13th Edition

$3$
The distance formula for two vectors can be calculated as: $d=\dfrac{|p \cdot q|}{|q|}$ Now, $p \cdot q=1(3)+2(5)+2(-2)=9$ and $|p \times q|=|9|=9$ Thus, $d=\dfrac{9}{ \sqrt {(1)^2+(2)^2+(2)^2}}$ or, $=\dfrac{9}{ 3}$ or, $=3$