Learn how to find equations of parallel lines, work out the gradient of perpendicular lines, and prove that given lines are parallel or perpendicular.

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.

Mathematicians, it's a rainy day but Susanna Post, the 2021 Arkansas Teacher of the Year, is on the hunt. Can you help in her scavenger hunt to find examples of parallel and perpendicular lines ...