### Theory:

Line parallel to the $$x$$ - axis:

Consider drawing a line parallel to the $$x$$ - axis. If the distance from the $$x$$ - axis and the line is the same, then the line can be represented as $$y = c$$ (where $$c$$ is a constant).

Line parallel to the $$y$$ - axis:

Consider drawing a line parallel to the $$y$$ - axis and the distance between the $$y$$ - axis and the line is the same, then the line can be represented as $$x = c$$ (where $$c$$ is a constant).
Example:
Consider plotting the points $$(-1,2)$$, $$(0,2)$$, $$(1,2)$$, $$(2,2)$$, and $$(3,2)$$ and joining them. We get a straight line.

Since the points are at the same distance ($$2 \ cm$$) from $$x$$ - axis. Then, the line is parallel to the $$x$$ - axis.