Copy of Theorem 11 - Three Parallel Lines Cutting a Transversal
This shows that if three parallel lines cut equal segments off the blue transversal then they will also cut equal segments off the red transversal.
Drag the points to change the position of the transversals.
Drag one of the parallel lines so that [DE] and [EF] are no longer equal. Are [AB] and [BC] now equal in length?