The Group of Blue Planar Isometries - WildTrig: Intro to Rational Trigonometry - N J Wildberger

Explore Euclidean isometries from a rational perspective in this 29-minute mathematics video. Focus on grounded isometries that fix the origin and derive formulas for projections and reflections with respect to a symmetric bilinear form. Examine reflections in a line through the origin, described by rational points on the circle and associated with rational slope parameters. Gain insight into the Weierstrass substitution in calculus and conclude with the formula for composing two reflections. Delve into the group structure of blue planar isometries and enhance your understanding of rational trigonometry.

Introduction
Reflections
Rationality
Weierstrass Substitution
Group Structure