Pappus' Theorem and Pascal's generalization (1/4)

Play with the points Juegue con los puntos Punto D = intersección de las líneas Ab y aB Punto E = intersección de las líneas Ac y aC Punto F = intersección de las líneas Bc y bC Pappus' Theorem (part 1/4) Let three points A, B, C be incident to a single straight line and another three points a,b,c incident to (generally speaking) another straight line. Then three pairwise intersections D = Bc∩bC, E = Ac∩aC, and F = Ab∩aB are incident to a (third) straight line. Pascal's theorem (parts 2/4, 3,4 y 4/4) is a generalization of Pappus's (hexagon) theorem Reference: http://en.wikipedia.org/wiki/Pascal's_theorem and http://www.cut-the-knot.org/pythagoras/Pappus.shtml