The perimeters of ∆ABC and ∆DEF are 30 cm and 18 cm respectively. ∆ABC ~ ∆DEF, BC and EF are corresponding sides. If BC =9 cm, then EF =__________ cm.
Since ∆ABC ~ ∆DEF,
∴ABDE=BCEF=ACDF=AB+BC+CADE+EF+FD⇒BCEF=3018=53⇒9EF=53 or EF=9×35 ⇒EF=275=5.4 cm
Hence, option B is the correct answer.