Here is an example where you can vary the angle of rotation. The original figure is rotated counterclockwise about the center of rotation F by the angle Beta shown on the slider at the bottom of the screen. You can change Beta by increments of 5 degrees at a time to see what happens to the image under this rotation (just click left or right on the slider, or click and drag Beta to watch what happens).[br][br]You can also move F and/or move vertices of the original figure. Have fun playing!