The Wallace-Simson Line
From a point P on the circumcircle, drop perpendiculars to the sides (extended) of the triangle. The feet of these perpendiculars are collinear. The line is known as the SIMSON LINE or the WALLACE-SIMSON LINE.
Arithmetic Sequences Find u(n) from u(1)
Ex1a. Reflection in the line x = 0
TWINS (15 May) Animation 2A
(1.1) Points, Lines and Planes
Upper and Lower Sum or Riemann Sum