A curved Parallel?

My math teacher said that only straight lines can be parallel.
I asked why can't straight lines? She said "because that's how it is."

I dislike this.

Why can't a circle within a circle, where the centres are the same only with a differing radius be parallel? Is a helix parallel?

People like you cause world wars.

hlo

http://mathworld.wolfram.com/ParallelCurves.html

Parallel is simply usually defined as a property of straight lines.

>>3
thank you

>>2
People like you cause the holocaust.

>>5

holocaust never fucking happened you retard. it's just a myth fabricated and perpetuated by jews to enduce sympathy from the international community while they rape palestine. now that they have gone too far, the truth is slowly coming out.

>>2
>>5
>>6
Same person.

Parallel has straight lines included in its own definition.

>>1
lol 4th grader

People like you are dangerous.I'd like to see lines be parallel and stay that way if u elongate them.Or turn them about a bit.And what's more is curves can't be parallel because of spheres and the interactivity beetween the normal 2-d plane upon wich we debate and the 3-d where big curves are quite appreciated from guys.Off subject of course.

In hyperbolic space, parellel lines are not streight.

As for the original question, a circle just isn't a line.  A circle is a collection of points defined by their common distance from another point.  Lines are lines because they have a given origin and slope.

In Mother Russia, parallel lines crook you!

Wait, come to think of it, I believe it was a Russian guy who started to mess with geometry like this.

>>11
A circle isn't a line because lines in math are always straight lines. Both lines and circles are types of curves though. That curves are collections of points has nothing to do with anything.