Exploring Parallel and Perpendicular Lines

Author:
Josh, Crawfoer
Explore The Slopes of lines that are parallel and Perpendicular to a given line (in red). Click Show Parallel or Show Perpendicular to get started. Drag the two original blue points to create a new starting line. (Drag point D to move the parallel line.)
Parallel Line: Create a few lines through two given points. Note the slopes of the original lines, and the slopes of the Parallel Lines. What do you notice about the slopes? Think of a rule that parallel lines have to follow. Perpendicular lines: Create a few lines through two given points. Note the slopes of the original lines and the slopes of the Perpendicular lines. What do you notice about the slopes? Think of a rule that perpendicular lines have to follow.