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.

**Point C i**

In this movie we move point C along a line parallel to AB (AB is the invariant line of the shear).

We pause at four salient postitions that we label C1, C2, C3 and C4.

The movie then reverses and hides the four points again.

You might ask

- *Can you remember the position of the four points?
- What is special about the points?
- Are there other such points?*

On the next page we show the same movie but with the resulting **base** and **height** of triangle ABC highlighted for the four positions of C.