Lecture 15 We continued discussing Book I of Euclid's Elements. Today's goal was to state at least Pythagoras' Theorem (Proposition 47). In particular we went over the proofs of the following Propositions: Proposition 34 Proposition 35 Proposition 37 Proposition 41 Proposition 46 Proposition 47 Click on the above links to go directly to the proofs and commentaries of the results.