2014/08/10 by Ivan Izmestiev, Izmestiev, Ivan
Mathematics · #Advanced Differential Equations and Dynamical Systems #FOS: Mathematics #History and Theory of Mathematics #Mathematics and Applications #Metric Geometry (math.MG)
paper · pdf · doi:10.48550/arxiv.1408.2247
openalex publication_date 2014/08/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
If there exists a cyclic quadrilateral whose sides go through the given four collinear points, then there are infinitely many such quadrilaterals inscribed in the same circle. We give two proofs of this porism; one based on cross-ratios, the other on compositions of hyperbolic isometries.