Perpendicular Distance (Leaving Cert Mathematics): Flashcards

Shortest distance measured along perpendicular line

$d = \frac{|ax_1 + by_1 + c|}{\sqrt{a^2 + b^2}}$

Coefficients from equation of the line

Coordinates of the given point

Ensures distance is non-negative

Normalises direction of the line

Shortest path between point and line

Point lies on the line

Negative reciprocal of original slope