Trochoid on a line

Drag the "d" slider to see the circle roll along the horizontal axis, or click once on the "d" slider button and use the keyboard up/down to adjust.
The "k" slider determines whether the path is drawn by a point on the edge of the circle (k=1), a point inside the circle (k<1), or a point outside the circle (k>1).

Jerome A. White, February 24, 2009, Created with GeoGebra