# Rolling One Parabola on Another

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The focus of a parabola that rolls around another fixed identical parabola describes a straight line, which is the directrix of the fixed parabola.

Contributed by: Izidor Hafner (August 2012)

Open content licensed under CC BY-NC-SA

## Snapshots

## Details

Reference

[1] J. Bryant and C. Sangwin, *How Round Is Your Circle?: Where Engineering and Mathematics Meet*, Princeton, NJ: Princeton University Press, 2008, pp. 44–45.

## Permanent Citation

"Rolling One Parabola on Another"

http://demonstrations.wolfram.com/RollingOneParabolaOnAnother/

Wolfram Demonstrations Project

Published: August 15 2012