The Product of the Circumradius and an Exradius
The Product of the Circumradius and an Exradius
Let ABC be a triangle with circumradius . Construct the excircle opposite A with excenter F and exradius . Let D and E be the intersections of the extensions of AB and AC with the excircle. Let G be the intersection of AF with the circumcircle of ABC. Then .
R
r
AF×GF=2Rr