home construction Thinking
Euclid
Tech
 foundation
intermediate
advanced
Euclid's Elements

euclidBook 1: The 48 Propositions
40 Equal triangles which are on equal bases and on the same side are also in the same parallels.
Let ABC, CDE be equal triangles on equal bases BC, CE and on the same side. Let AD be joined. Please enable Java for an interactive construction (with Cinderella).