Given an triangle ABC isosceles at the vertex A, let P and Q be the touchpoints with AB and AC, respectively with the circle T, which is tangent to both and is internally tangent to the circumcircle of ABC. Let R and S be the points of the circumscribed circle of ABC such that AP=AR=AS . Prove that RS is tangent to T . geometrymixtilinear incircletangentisosceles