Reference:
1. http://aleph0.clarku.edu/~djoyce/java/elements/bookVI/propVI9.html
2. Lichtfield, D., Goldenheim, D., & Dietrich, C. H. (1997). Euclid, Fibonacci, and Sketchpad. The Mathematics Teacher, 90(1), 8–12.
3. http://www.cut-the-knot.org/triangle/n-parts.shtml
