Editing Brianchon's theorem (section)

{{short description|The 3  long diagonals of a hexagon tangent to a conic section meet in a single point}}
[[File:Brianchon-6-tangents.svg|300px|thumb|Brianchon's theorem]]
In [[geometry]], '''Brianchon's theorem''' is a theorem stating that when a [[hexagon]] is [[circumscribed]] around a [[conic section]], its principal [[diagonal]]s (those connecting opposite vertices) meet in a single point. It is named after [[Charles Julien Brianchon]] (1783–1864).