Interactive geometry to use now

Pascal's theorem Three points, 1,2,3 and 1',2',3', are marked in green on a circle and then joined as shown. What can you say about the three points where the joins meet? If you can't see it, ask for Hint 1. Rearrange the six points to form a hexagon. What can you say about the points where opposite sides meet? If you can't see it, ask for Hint 2 Press "r" to reset the sketch. These problems are taken from "You Are A Mathematician" by David Wells (Penguin,1995)