Straight lines can be drawn in any direction. Horizontal lines go left and right. Vertical lines go up and down. Parallel lines are a fixed distance apart and will never meet, no matter how long they ...

If you took Geometry in High School, you almost definitely learned it as a subject based on rules and axioms discovered by the ancient Greeks. The details of this subject, which I must admit was ...

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.