Originally Posted by

**Plato** On one level this is a totally meaningless question.

Consider the points $\displaystyle A;(1,3),~B:(2,4),~C:(1,2),~\&~D:(2,3)$

If one plots those four point it is transparently clear that **those four points are not collinear**.

BUT $\displaystyle \overrightarrow {AB} = \overrightarrow {CD} $!

Under any common understanding of the language, don’t you think that a vector ought to be collinear with itself?

Do those two vectors * form segments of the same ray*?

NO! This is just a problematic question. The author may not fully understand the mathematical status of *vectors*

A vector is an equivalence class of object having the same *direction* and same *length*.

Thus two non zero **vectors** are collinear if and only if they are multiples of each other.