Editing Incircle and excircles (section)

==Generalization to other polygons==
Some (but not all) [[quadrilateral]]s have an incircle. These are called [[tangential quadrilateral]]s. Among their many properties perhaps the most important is that their two pairs of opposite sides have equal sums. This is called the [[Pitot theorem]].<ref>{{harvtxt|Josefsson|2011|loc=See in particular pp.&nbsp;65–66.}}</ref>

More generally, a polygon with any number of sides that has an inscribed circle (that is, one that is tangent to each side) is called a [[tangential polygon]].