Higher - The gradients of two perpendicular lines will always multiply to make –1. Make sure you are familiar with finding the equation of a line and calculating gradient to understand equations of ...

Horizontal lines run left to right, parallel to the horizon, with slope 0 and equation y = k. Vertical lines run top to bottom, perpendicular to the horizon, with undefined slope and equation x = k.

Whether you are sketching graphs in mathematics, understanding directions in geography, or reading blueprints in design class, horizontal and vertical lines are concepts you cannot avoid. They form ...