C-03-Q080mediumsingle_mcqIn △PQR\triangle PQR△PQR with centroid OOO, PQ2+QR2+PR2=PQ^2 + QR^2 + PR^2 =PQ2+QR2+PR2=aOP2+OQ2+OR2OP^2 + OQ^2 + OR^2OP2+OQ2+OR2