Question

I have to prove this statement: Euclidean parallel postulate equivalent pythagorean.
Someone gave me the proof of pythagorean but I don't see the link between Euclidean parallel postulate and pythagorean.
Someone helps me, please.

Answer 1

@wio

Answer 2

honestly it's very hard to see the connection

Answer 3

Among the proofs, 112 proof for pythagorean, I tried to figure out which one using Euclidean parallel postulate but I failed.
Surely, to show the Euclidean implies pythagorean, we need a proof which used // postulate to prove
to show pythagorean implies //, we do backward. But it seems I failed on figuring out which proof has both sides like that. :(

Answer 4

http://www.cut-the-knot.org/triangle/pythpar/PTimpliesPP.shtml
this is the most referenced article I've seen