The next type of transformation we shall look at is called a rotation. Click the "On/Off" button on the applet to start it.
As before, the brown circle is the object and the blue one the image. You can drag the object (brown) with the mouse. Watch what happens to the image.
The black dot represents the center of rotation. A line through the object and the center of rotation meets a line through the image and the center of rotation at a fixed angle called the angle of rotation.
We can move the center of rotation and also adjust the angle of rotation. If you click on the "Mode" button, two tiny red dots will appear, one on the center of rotation and the other at the head of an arrow on the diagram representing the angle of rotation. Here are a few things for you to investigate.
If I told you that the object and the image were in the same place, where would they be? Such a point is called a fixed point for the transformation.
How is the distance of the image from the center of rotation related to the distance of the object from the center of rotation?
e-mail: C. Mawata