Euclid's Elements Book 1: Proposition 30, Relationship Between Parallel Lines

[@ThePugSisters]

How come you can’t use prop 29 again but on the alternate angles on EF and CD so that angle EHK will be equal to GHF becuase they are vertical angles due to prop 15, so GHK will equal HKD?

[@wmhemphill8642]

You are awesome.

[@matheusmiotto7472]

any ideas of how do I prove this poposition is equivalent to the 5th postulate?

[@EulersAcademy]

Thank you for watching. At this point, I'm unsure, but I will keep your question in mind when I start working on Euclid again later this year.

[@everestleo4147]

ah

[@prod_e4gle]

what software is this

[@EulersAcademy]

Thank you for watching. I use Camtasia to screen record and I use Autodesk Sketchbook for my blackboard.

[@charlietittmann575]

Couldn't you just use common notion 1 (Things which equal the same thing also equal one another)?

[@gigimesa6307]

equal, not parallel