AP = AO + OP = 4 + 8 = 12 cm and AS = 4 cm∴ PS2 = 122 – 42⇒ PS = 8√2 cmNow ΔASP and ΔRQP are similar;∴ AS/RQ = SP/QP⇒ 4/RQ = 8√2/16⇒ RQ = 64/8√2⇒ RQ = 4√2 cm