I took M490 “Problem Seminar” (a math class) in 1995 with Dr. Hofstadter - we studied triangles, and the definition of a triangle’s center. You would think tha

I took M490 “Problem Seminar” (a math class) in 1995 with Dr. Hofstadter - we studied triangles, and the definition of a triangle’s center. You would think that there is a limited set of “triangle centers” but he showed us (and he had us discover and draw them out using The Geometer's Sketchpad) dozens of ways to find triangle centers and he had notes on hundreds more definitions of triangle centers. His approach to teaching was fun and made us want to take on challenging problems. :)