How Chromogeometry Transcends Klein's Erlangen Program for Planar Geometries - N J Wildberger
Insights into Mathematics via YouTube
Overview
Syllabus
Note: Around the diagram for the green geometry has one of the "green squares" incorrectly drawnthe one with area 18 --it too should be a parallelogram.
Intro to three-fold symmetry in planar geometry
Quadrance between points
Pythagoras and Triple quad formula
Spread between lines
Spread as a normalized squared determinant
Laws of affine rational trigonometry
Thales' theorem
Proof of Cross law
Blue Pythagoras
Red Pythagoras
Green Pythagoras
Coloured altitudes
Blue Euler line
Red Euler line
Green Euler line
Omega triangle
Omega triangle and more
Blue ellipse and its diagonals
Red ellipse
Green ellipse and diagonals
Three sets of foci and directrices
A chromatic parabola
References
Taught by
Insights into Mathematics