Here a point S moves on a circle that goes through O.

It looks as though the result is a straight line (through the points of intersection of the two circles, of course...).
We can prove this using the converse of the proof outlined on the Method A4 page.

In the movie on the next page, point S moves on a circle that does not pass through O.
What will the trace of the image look like?

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.