## Polar coordinates questions [closed]

Using polar coordinates, create a system with a fixed point at the origin, and with infinitely many periodic orbits which alternate between clockwise and counterclockwise flows.

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math.stackexchange.com/questions/31015/… – Andres Caicedo Apr 5 2011 at 2:51
mathoverflow.net/faq#whatnot – Yemon Choi Apr 5 2011 at 3:21