The incircle or inscribed circle of a triangle is the largest circle contained in the triangle. It touches (is tangent to) the three sides. The center of the incircle is called the triangle's incenter which can be found as the intersection of the three internal angle bisectors.
It this picture fiind the incenter, the three angle bisectors and, the points where the circle touch the triangle and the radius of the incircle (also known as the inradius, r )
Marilena Faiciuc, Creat cu GeoGebra