Trochoid around a circle
Drag the "α" slider to see the orbiting circle roll around the central
circle, or click once on the "α" slider button and use the keyboard
up/down to adjust.
The "s" slider determines whether the orbiting circle rolls
inside or outside of the central circle.
The "k" slider determines whether the path is drawn by a point on the
edge of the orbiting circle (k=1), a point inside the circle (k<1),
or a point outside the circle (k>1).
The "R1" and "r2" sliders adjust the radii of the circles.
Jerome A. White, Created with GeoGebra