Let ABCD be a cyclic quadrilateral with AB<CD, and let P be the point of intersection of the lines AD and BC.The circumcircle of the triangle PCD intersects the line AB at the points Q and R. Let S and T be the points where the tangents from P to the circumcircle of ABCD touch that circle.(a) Prove that PQ=PR.(b) Prove that QRST is a cyclic quadrilateral. OMCCgeometrycyclic quadrilateralcircumcircle