Why can lines not be congruent?

Let's start with the definition. Definition: Line segments are congruent if they have the same length So lines and rays would be congruent if they had the same length. However, Rays and lines cannot be congruent because they do not have both end points defined, and so have no definite length. It know it's a LONG story, the the bottom LINE is they have no length so they can't be congruent.