Coxeter - Figure 1.6 D (left)
A, B, C, D are any four collinear points. R is a point outside the line and T, Q, W are the sections by an arbitrary line through D. Z is the intersection of AQ and RC.
Yanisa Poongthaisong B3 Qtr1Project
Rotation of Triangle HKJ 75 CW about R on HJ