Rolling curve / 17
Epitrochoid
Geometry
An epitrochoid traces a pen carried by a circle rolling outside a fixed circle.
x(t) = (R + r)·cos t − d·cos((R + r)/r · t)
y(t) = (R + r)·sin t + d·sin((R + r)/r · t)
Adjust a slider to redraw · Save PNG & Save GIF export · Animate traces the curve · the first slider auto-sweeps