Chebyshev's linkage - alternative form

It is indeed curious that more than one linkage can generate a particular curve.
Have a play with the GeoGebra applet below, in which the two forms of Chebyshev's linkage are superimposed.

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and activated. (click here to install Java now)

Chris Sangwin, 22 Dec 2006, Created with GeoGebra