Coordinate Geometry

Coordinate geometry turns geometry into algebra. Nearly every P1 paper has a straight-line question, and they are reliable marks once you know the formulae.

The three formulae

For two points $A(x_1, y_1)$ and $B(x_2, y_2)$:

Gradient: $m = \dfrac{y_2 - y_1}{x_2 - x_1}$