User:S Larctia/Maths/Coordinate geometry

Consider a line, with gradient $$ m$$, which passes through the point A at coordinates $$ (x_1 $$,$$ y_1) $$. Suppose that point P, at $$ (x $$,$$  y) $$, is also on the line.
 * Then:
 * $$ m = \frac {y - y_1}{x - x_1} $$
 * And by trivial rearrangement, the equation of the line is:
 * $$ {y - y_1} = m({x - x_1}) $$