ik im the one who asked this but i solved it and the answer is: 16*(sqrt10)/5 Since triangle RQT is isosceles, we have ST=QT−QS=QR−QS=8−3=5. From △QTR∼△RST, we have RTST=QRRT, so RT2=ST⋅QR=5⋅8=40.Hence, RT=√40=2√10. From △PQR∼△QRT, we have PQQR=QRRT, so that PQ=QR2RT=822√10=16√105.