Let ABC be a triangle . Let point X be in the triangle and AX intersects BC in Y . Draw the perpendiculars YP,YQ,YR,YS to lines CA,CX,BX,BA respectively. Find the necessary and sufficient condition for X such that PQRS be cyclic . geometryparallelogramrectanglegeometric transformationhomothetycircumcirclecyclic quadrilateral