What is the shortest distance from a point to a line?

A line from the point that intersects the other line line perpindicularly.

Given line    Ax + B + C  = 0     and point (m,n) .....the shortest distance beween the point and the line is given by :   

l Am + Bn  + C l

√ [ A^2 + B^2 ]

Here's the proof   [Note....the algebra gets a llttle sticky...!!!  ]

http://www.intmath.com/plane-analytic-geometry/perpendicular-distance-point-line.php