# Extouch Triangle in Poncelet Porism

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A Mathematical Droodle

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Copyright © 1996-2018 Alexander BogomolnyThe applet attempts to illustrate a property of the extouch triangles involved in the Poncelet porism: given two circles, O(R) and I(r), let ABC be a generic triangle inscribed into O(R) for which I(r) serves as an excircle. If d, the distance between the centers of the circles satisfies

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... to be continued ...

### References

- L. Emelyanov and T. Emelyanova,
__Euler’s Formula and Poncelet’s Porism__,*Forum Geometricorum*, Volume 1 (2001) 137–140 - W. Gallatly,
*The Modern Geometry of the Triangle*, Scholarly Publishing Office, University of Michigan Library (December 20, 2005)

#### Poncelet Porism

- Poncelet's Porism
- Extouch Triangle in Poncelet Porism
- Fuss' Theorem
- Intouch Triangle in Poncelet Porism
- Euler's Formula and Poncelet Porism
- Poncelet Porism in Ellipses

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Copyright © 1996-2018 Alexander Bogomolny71764758