Roulette (Hypotrochogon) of a Polygon Rolling inside a Circle

This Demonstration shows the roulette drawn by a point attached to a regular polygon rolling without slipping inside a circle.
This roulette curve is a sequence of circular arcs traced by the polygon when rolling along the edge of the circle.
For generalized cyclogons [1] and generalized trochoidal curves [2], these roulettes can be considered as limiting cases of hypotrochogons with an infinite number of vertices of the base (stationary) polygon.
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    [1] T. M. Apostol and M. A. Mnatsakanian, "Generalized Cyclogons," Math Horizons, 2002 pp. 25–28.
    [2] T. M. Apostol and M. A. Mnatsakanian, "Area & Arc Length of Trochogonal Arches," Math Horizons, 2003 pp. 24–30.
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