Transformations - Rotation

Jon Ingram
Exploring rotation
Use this sketch to play around with rotation. You can move the blue points, and select what is displayed, and what is hidden. Questions: For 90 degree and 180 degree rotations, can you predict what will happen to the image when you move a) the source, and b) the centre of rotation? Is there any way to figure out where the centre of rotation is, if it is hidden?