How many sides does a line have? How about a line in 3D space?

Question

Then how come people say that a circle has 2 or 1 side or something like that? Isn't a circle a line too?

If a circle can divide the plane into 2 regions, doesn't a line divide the plane into 2 regions? Why do we say that a cirlce has sides, but a line does not?

Answer 1

The line itself is a mathematical figure. It has no physical form so it cannot have sides. It is possible, however, to be on one side of a line or another, but this has less to do with the line than the area that it marks and separates.

That's really your answer in a nutshell. If you're thinking of a line as a figure of geometry, it has no sides because it has no substance. If you're thinking of a line as a separator, then it has 2 sides in 2-dimensional space and infinite sides in 3-dimensional space.

Answer 2

How many sides a figure has depends on where is is embedded. So, a line in a plane has 2 sides and a line in 3D space has 1 side. Similarly, a circle in a plane has 2 sides and in 3D space has one side. But the central circle of a Mobius strip has only one side.

Answer 3

You need to define the term. The "sides" of a polygon or polyhedron are determined by the number of line or plane segments it's made of. An object with effectively infinite dimensions (such as a line or a plane) has two sides in the dimension immediately beyond its minimum expression (2-D for a line, 3-D for a plane). But beyond that, the term "sides" is meaningless.

In 2-D, a line can have two "sides", determined by the location of the line itself. In 3-D, a true line has infinite length but no other dimension. The only "side" is outside, in an infinite number of directions along a plane perpendicular to the line. You could break the vectors down into Cartesian coordinates, expressing them in two dimensions, but that's a mathematical convention, not reality. You can't talk about "ends" (unless you mean a line segment), because there are no ends to a true line.

A circle can have two "sides" (In 2-D: inside and outside, In 3-D: one side or the other of the plane in which the circle is contained). That's because it has finite dimensions. But it can also have infinite "sides" because it can be defined as an infinite number of line segments with adjoining angles approaching zero degrees. (The [out]side at 175 degrees is opposite the side at the angle of 355 degrees but perpendicular to the side at 85 degrees, for example.)

Answer 4

All the answers you have gotten so far are right by all standards but picture this it has 5. 1-top 2-bottom 3-middle 4-left end 5- right just something for people to talk about. As for a 3-dimensional i have no clue. Good luck

Answer 5

A line has one dimension.
If you connect the ends together the line is still single dimensional.
It encloses a two dimensional space.

Answer 6

A line, mathematically speaking, is simply a visual connection between two points. It does not have any sides or any mass or anything. It does not exist. It is just for you to see a connection.

Answer 7

A line is, by definition, a 1-dimensional object, so it has no sides, just ends.

Answer 8

A line goes on and on in a straight line for ever never bending. it is only 1 dimensional.

Answer 9

ive done computerized engineering for a while a line has no sides even rotated 3d it would need some offset thickness to make it have sides