ΔABC ~ ΔDEF and the area of ΔABC is 13.5 cm2 and the area of ΔDEF is 24 cm2. If BC = 3.15 cm, then the length (in cm) of EF is:

4.8 3.9 5.1 4.2

4.2

\(\frac{area\;of\;ABC}{area\;of\;DEF}\) = (\(\frac{BC}{EF}\))2 = \(\frac{13.5}{24}\) = (\(\frac{3.15}{EF}\))2 = \(\frac{13.5}{EF}\) = \(\frac{3}{4}\) = EF = \(\frac{3.15 \;×\; 4 }{3}\) = 4.2 cm = EF = 4.2 cm. Therefore, EF is 4.2 cm.