Geometry · lesson 3

Parallel and Perpendicular

Parallel lines copy the slope and change nothing. Perpendicular lines flip it and change the sign. Watch the line swing a quarter turn until the corner is square.

PARALLEL m₂ = m₁|PERPENDICULAR m₁ × m₂ = −1Parallel: copy the number. Perpendicular: flip it, then change the sign.
Step 1

Here is line 1

Its slope is drawn as a staircase: over, then up.

  1. The work will print here, one line at a time.
Projecting? Press Space for the next step.
Try another
the first line parallel line perpendicular line

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