Bilhar de Poncelet

Abstract

In Applications dAnalyse et de G´eom´etrie, 1862, Poncelet presents a work about pairs of conics holding an inscribe polygon at one and simultanealy circunscribe at another. He proves that when there exists a polygon satisfying this property,then there exist infinitely many polygons with the same number of edges satisfying its too. In this work we are interested to study the varieties of pairs of conics related by polygons, particularly triangles. We construct a fibration over a space of configurationsof degenerate triangles and we use it to recover the bidegree of the variety of pairs of conics related by triangles employing techniques of intersection theory.