# Coplanar vectors

## Main Question or Discussion Point

Two free vectors are always coplanar.

Then if A and B are free vectors, are A, B, and A+B all coplanar in all cases?

Mark44
Mentor
Two free vectors are always coplanar.

Then if A and B are free vectors, are A, B, and A+B all coplanar in all cases?
Yes.
Any two vectors that start from the same point (you can assume that they start from the origin) determine a plane. Any linear combination of these vectors (including 1*A + 1*B) also lies in that same plane.

Cool.

If two vectors are linearly dependent, they are collinear. They are always coplanar.

If three vectors are linearly dependent, they are coplanar. Three vectors are always all co"cubeular" (I don't know a word like coplanar for a three dimensional object.)

Based on this pattern, it correct to say that:

If n vectors are linearly dependent, then they are co(n-1 space object) and are always co(n space object).

Since for two vectors, an n-1 space object is a line, for three it is a plane, and so on.

Am I making sense?

Last edited:
Mark44
Mentor
Cool.

If two vectors are linearly dependent, they are collinear. They are always coplanar.
Yes. If two vectors are linearly dependent, then each is a nonzero scalar multiple of the other.
If three vectors are linearly dependent, they are coplanar.
They could be collinear, depending on which vectors we're talking about.
Three vectors are always all co"cubeular" (I don't know a word like coplanar for a three dimensional object.)
I don't believe there is any special terminalogy beyond coplanar.
Based on this pattern, it correct to say that:

If n vectors are linearly dependent, then they are co(n-1 space object) and are always co(n space object).

Since for two vectors, an n-1 space object is a line, for three it is a plane, and so on.

Am I making sense?
Yes, I get what you're saying, but as I said, I don't believe there is any terminology beyond coplanar.