The three parallel lines theorem is another theorem that provides a ratio between line segments created by a transversal of parallel lines, similar to the Intercept Theorem.

Can there be 3 parallel lines?

Similarly, three or more parallel lines also separate transversals into proportional parts. If three or more parallel lines intersect two transversals, then they cut off the transversals proportionally.

How do you prove three lines are parallel?

The first is if the corresponding angles, the angles that are on the same corner at each intersection, are equal, then the lines are parallel. The second is if the alternate interior angles, the angles that are on opposite sides of the transversal and inside the parallel lines, are equal, then the lines are parallel.