## Perpendicular to Parallel
That's right, if you rotate a perpendicular line by 90° it will become parallel (but not if it touches!), and the other way around.
## Parallel CurvesCurves can also be parallel when they are always the same distance apart (called "equidistant"), and never meet. Just like railroad tracks. The red curve is parallel to the blue curve in both these cases:
## Parallel SurfacesSurfaces can also be parallel, so long as the rule still holds:
## Mind BenderSomething that makes my mind bend: we know that if we have two parallel lines, and we rotate one by 90°, they will be perpendicular to each other, right? Well, does the same apply to curves? Can you have "perpendicular curves", by rotating one of them by 90°? I simply don't know, but it is fun to think about. |