Double-click on the movie to PLAY.

Click once to PAUSE.

RELOAD the page or double-click to return to the START of the movie.

Method B3

Here we lower point A by another unit, so the invariant line has a gradient of 2.
What will happen to the position of C' and to the shape of the green image? You might still find that the shape is quite hard to visualise.

Does the area of the green image stay unchanged?

The next page provides a JAVA worksheet that allows you to move points A and B or the whole invariant line.