Starvard
Geometry in bold colour
Euclid's geometry rebuilt in bold colour, proof by proof.
In 1847 Oliver Byrne printed Euclid's geometry with coloured shapes in place of letters, so readers could follow a proof by looking. Nicholas Rougeux rebuilt the whole book for the web, with clean diagrams and the same bright reds, yellows and blues.
Proofs that once felt like a wall of text become small, satisfying puzzles. It is as lovely to browse as it is useful to study.
Try this first
Open Book 1 and pick a proposition whose diagram catches your eye, then follow the coloured shapes instead of the letters. Proposition 47 is the famous one: the Pythagorean theorem, drawn so clearly it feels obvious.
Good to know
Oliver Byrne's original 1847 book is public domain. This web rebuild is Nicholas Rougeux's careful work, so we link to it rather than copy it.
Keep exploring
Treasures are wonderful free things made by other people. Starvard gathers them with admiration; the credit is all theirs.