r2027

Let I be the incenter, A'B'C' the incentric triangle. Let R be the radical center of the ninecircles of AIB', BIC', CIA' and S the radical center of the ninecircles of AIC', BIA', CIB'. The midpoint M of RS lies in the line OI (O  circumcenter) and the isogonal of the infinite point of RS is X(100).


inici