![](http://sciences.heptic.fr/wp-content/uploads/2021/08/p1362-equilateral-triangle-inscribed-circle-lunula-area-570x350.gif)
From Gogeometry Using : Isometric transformation Inscribed angles in a circle Equilateral triangle Tangents to a circle Define R radius of circle O and r radius of circle Q By construction and symmetry A, O, Q, D are collinear DE=DF, AE=AF AD angle bisector of ∠BAC D symmetric of A […]