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.

N then P

Here we show the effect on square ABCD of shear N followed by shear P.

We round things off by using a static diagram to take a more analytic view of the shears.
We start with the pair M then N: MN-analysis
We then consider the pair N then P: NP-analysis.