Perpendicular Distance from Straight Line in Plane to Point/General Form

Theorem
Let $\LL$ be a straight line embedded in a cartesian plane, given by the equation:
 * $a x + b y + c = 0$

Let $P$ be a point in the cartesian plane whose coordinates are given by:
 * $P = \tuple {x_0, y_0}$

Then the perpendicular distance $d$ from $P$ to $\LL$ is given by:


 * $d = \dfrac {\size {a x_0 + b y_0 + c} } {\sqrt {a^2 + b^2} }$