ΔABC is similar to ΔDEF is area of ΔABC is 9 sq. cm. and area of ΔDEF is 16 sq. cm. and BC = 21 cm. Then the length of EF will be:

Answer: Option B

Solution

Answer: Option B

Solution:

∵ ΔABC ≅ ΔDEF

$$\begin{array}{rl}& \therefore \frac{AB}{DE}=\frac{BC}{EF}=\frac{\sqrt{9}}{\sqrt{16}}\\ & =\frac{2.1}{EF}=\frac{3}{4}\\ & EF=2.8\text{cm}\end{array}$$