Proof: By Euclid
(related to Corollary: 5.19: Proportional Magnitudes have Proportional Remainders)
Thank you to the contributors under CC BY-SA 4.0!
- Health L. Thomas (Transl.): "Euclid's Elements - all thirteen books", Green Lion Press, 2013,
- Byrne, O.: "The First Six Books of the Elements of Euclid, in Which Coloured Diagrams and Symbols are used Instead of Letters", London William Pickering, 1847