In this lesson I will teach you how to prove if two or more lines are parallel. Now, I want to be very clear that we will focus on proving lines parallel- not if two parallel lines intersect. If you recall in my lesson on theorems and postulates I used the fact the mathematicians have not been able to prove two parallel lines intersect- however, we assume that they don’t and we express this concept as a postulate. All we are doing in this lesson is looking at the relationship between two lines and seeing if conditions exists such that we can prove the lines are parallel. Please ensure that you watched all the previous lessons in this chapter as we will use the properties and theorems in those lessons in our proofs. Now, if you’re feeling overwhelmed by all this – take a step back and review and of course watch the videos as much as you like. Remember we are studying pretty abstract concepts and so give yourself time to fully comprehend new skills and knowledge. Good luck!