Link: https://www.youtube.com/playlist?list=PL6ACFCC19EA82CA71
List
- Intro
- Apollonius and polarity
Introduction
- Distance and Angle not good for understanding hyperbolic geometry
- new story: Apollonius.. conics… polarity… Minkowski… rational trigonometry
- Quadrance+Spread.png
- hyperbolic triangle geometry becomes a new vibrant subject
Apollonius and polarity
- connection/duality between point and line
- a is the pole of A
- A is the polar of a

Perp.png
- polar independence theorem : the polar A does not depend on the choice of lines thru a
- polar duality theorem : if a lies on b perp, then b lies on a perp, vice versa
