Completed
Proof of Cross law
Class Central Classrooms beta
YouTube videos curated by Class Central.
Classroom Contents
How Chromogeometry Transcends Klein's Erlangen Program for Planar Geometries - N J Wildberger
Automatically move to the next video in the Classroom when playback concludes
- 1 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.
- 2 Intro to three-fold symmetry in planar geometry
- 3 Quadrance between points
- 4 Pythagoras and Triple quad formula
- 5 Spread between lines
- 6 Spread as a normalized squared determinant
- 7 Laws of affine rational trigonometry
- 8 Thales' theorem
- 9 Proof of Cross law
- 10 Blue Pythagoras
- 11 Red Pythagoras
- 12 Green Pythagoras
- 13 Coloured altitudes
- 14 Blue Euler line
- 15 Red Euler line
- 16 Green Euler line
- 17 Omega triangle
- 18 Omega triangle and more
- 19 Blue ellipse and its diagonals
- 20 Red ellipse
- 21 Green ellipse and diagonals
- 22 Three sets of foci and directrices
- 23 A chromatic parabola
- 24 References
