Parallel lines are straight lines which have the ... We've already seen that intersecting lines create vertically opposite angles that are equal. The lines make an X shape. Co-interior angles ...

The diagonal line is a transversal as it is crossing the pair of parallel lines. When two lines intersect, the opposite angles are equal. Alternate angles are on opposite sides of the transversal ...

This theorem dictates that vertically orientated, alternate interior angles of two ... other angle mirroring the opposite side. This example occurs when two parallel lines are intersected by ...