3.5 Inefficient proof of the 3rd parallel theorem
Show Description Hide DescriptionGeometry: 3.5 (Inefficient) Proof of the "3rd Parallel" Theorem http://www.screenr.com/MmZ

I can prove two lines are parallel given they are both parallel to a same 3rd line.


Pause the video and take a moment to think through how you would prove this.

From this point on, you can call this idea we are proving the "3rd parallel theorem" in a proof.

What if I had done angles 1 and 4 in my proof? Would that have made this proof shorter?

My proof could have been two steps shorter if...
