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 B+

This shows several points in the plane being rotated through 90˚ about A and then B.
Can you see the single transformation that would take the points to their final position?
Which point returns to its starting place?

The same thing is shown on this JAVA worksheet.