Let ABC be a isosceles triangle with AB=AC an D be the foot of perpendicular of A. P be an interior point of triangle ADC such that m(APB)>90 and m(PBD)+m(PAD)=m(PCB).
CP and AD intersects at Q, BP and AD intersects at R. Let T be a point on [AB] and S be a point on [AP and not belongs to [AP] satisfying m(TRB)=m(DQC) and m(PSR)=2m(PAR). Show that RS=RT trigonometrygeometrycircumcircleprojective geometrygeometry proposed