College Geometry: An Introduction To The Modern... — Legit

: Detailed study of the line formed by the feet of the perpendiculars from a point on the circumcircle to the sides of a triangle.

A significant portion of the work is dedicated to specific "remarkable" circles and lines that reveal deeper symmetries in simple shapes: College Geometry: An Introduction to the Modern...

Synthesis of Modern Euclidean Principles: A Review of Altshiller-Court’s "College Geometry" : Detailed study of the line formed by