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:

Solution (By Examveda Team)

∵ ΔABC ≅ ΔDEF

$$\eqalign{ & \therefore \frac{{AB}}{{DE}} = \frac{{BC}}{{EF}} = \frac{{\sqrt 9 }}{{\sqrt {16} }} \cr & = \frac{{2.1}}{{EF}} = \frac{3}{4} \cr & EF = 2.8\,{\text{cm}} \cr} $$