We consider circular annuli with Poncelet's porism property. We prove two identities which imply Chapple's, Steiner's and other formulas. All porisms can be expressed in the form in which elliptic functions are not used.
@article{bwmeta1.element.doi-10_2478_v10062-010-0011-0,
author = {Waldemar Cie\'slak and El\.zbieta Szczygielska},
title = {On Poncelet's porism},
journal = {Annales UMCS, Mathematica},
volume = {64},
year = {2010},
pages = {21-28},
zbl = {1220.53007},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.doi-10_2478_v10062-010-0011-0}
}
Waldemar Cieślak; Elżbieta Szczygielska. On Poncelet's porism. Annales UMCS, Mathematica, Tome 64 (2010) pp. 21-28. http://gdmltest.u-ga.fr/item/bwmeta1.element.doi-10_2478_v10062-010-0011-0/
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