# coplanar vectors

by 1MileCrash
Tags: coplanar, vectors
 P: 1,060 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?
Mentor
P: 19,740
 Quote by 1MileCrash 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.
 P: 1,060 Cool. How about this: 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?
Mentor
P: 19,740

## coplanar vectors

 Quote by 1MileCrash Cool. How about this: 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.
 Quote by 1MileCrash If three vectors are linearly dependent, they are coplanar.
They could be collinear, depending on which vectors we're talking about.
 Quote by 1MileCrash 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.
 Quote by 1MileCrash 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.

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