Go to Euclid's Elements
/Book I

A small guide to the following pages

The propositions on the following pages are all illustrated with an interactive figure like the one you see here:

At the bottom of each figure there are a couple of buttons. Third button from the left moves you one frame forward. Try it out (point I should appear after the first click). Some of the details have been hidden, so sometimes you will have to press a couple of times for something new to appear. E.g. nothing new appears in frames 7 to 17 and frame 19 in the above figure. You can also interact with the figure by dragging some of the points and lines. Try dragging point A and D. Interacting with the figures might help you gain a deeper understanding of the mathematics behind the propositions.

You will find a proof next to all the interactive figures. The structure of every proof is taken from our main source [Densmore, ed.], but we have rephrased the proof as much as possible in an attempt to make the work of Euclid more accesible to a wider audience.

Worth noting:

• Right angles are indicated by a dot in the middle of the angle:
• A square marks the end of a proof:

References:

• [Densmore, ed.], Euclid's Elements, Green Lion Press 2003.
  
  

Go to Euclid's Elements
/Book I