English

Billiards in ellipses revisited

Metric Geometry 2020-01-28 v2 Differential Geometry Dynamical Systems

Abstract

We prove some recent experimental observations of D. Reznik concerning periodic billiard orbits in ellipses. For example, the sum of cosines of the angles of a periodic billiard polygon remains constant in the one-parameter family of such polygons (that exist due to the Poncelet porism). In our proofs, we use geometric and complex analytic methods.

Keywords

Cite

@article{arxiv.2001.02934,
  title  = {Billiards in ellipses revisited},
  author = {Arseniy Akopyan and Richard Schwartz and Serge Tabachnikov},
  journal= {arXiv preprint arXiv:2001.02934},
  year   = {2020}
}

Comments

12 pages, 9 figures

R2 v1 2026-06-23T13:06:49.579Z