What characteristic is true for parallel lines?

Parallel lines have a consistent and defining characteristic: they maintain the same slope. This means that when two lines are parallel, regardless of where they are on a coordinate plane, they will never converge or touch each other. The equality of their slopes ensures that they extend infinitely in both directions without intersecting, thereby fulfilling the definition of parallelism in geometry.

This unique relationship between parallel lines is essential when analyzing linear equations, as it informs geometric properties and calculations related to angles, areas, and other measurements in two-dimensional space. In contrast, slopes that are different would indicate that the lines are intersecting at some point, and congruence is not a typical consideration in the context of parallel lines since congruent figures pertain to shapes with the same size and shape, which does not apply here.