Mathematics · Glossary

What is Collinear vectors?

Definition 15.3 High School Mathematics · Chapter 15 — Vectors and Lines in the Plane

Two vectors are collinear if one is a scalar multiple of the other: v=λu\vec v = \lambda \vec u for some λR\lambda \in \R (or u=0\vec u = \vec 0). Geometrically: they have the same direction, or one of them is zero.

Examples

Example 15.6

u(3,2)\vec u\,(3, -2) and v(6,4)\vec v\,(-6, 4): det=3×4(6)×(2)=1212=0\det = 3 \times 4 - (-6) \times (-2) = 12 - 12 = 0, collinear (indeed v=2u\vec v = -2\vec u). u(3,2)\vec u\,(3, -2) and w(2,1)\vec w\,(2, 1): det=3+4=70\det = 3 + 4 = 7 \neq 0, not collinear.

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