Chapter 12 - Vectors and the Geometry of Space - 12.5 Equations of Lines and Planes - 12.5 Exercises - Page 872: 69

$\sqrt {\frac{61}{14}}$

Distance formula is given as: $d=\frac{|a \times b|}{|a|}$ Cross product: $a \times b=\lt 6,-3,4\gt$ $|a \times b|=\sqrt {6^2+(-3)^2+4^2}=\sqrt {61}$ $d=\frac{\sqrt {61}}{\sqrt {14}}$ or, $d=\sqrt {\frac{61}{14}}$