Question

∆ ABC ~∆DEF and their areas are respectively 64cm2 and 121cm2 if EF=15.4cm then find BC

Answer 1

∆ABC~∆DEF...,..........given
Now,
By similar triangle theorem we get,
∆ABC2 /∆ DEF2 = BC2 / EF2
64/121 = BC2/(15.4)2
By taking square roots of both sides,
8/11= BC/15.4
By cross multiplication,
(15.4×8)/11 = BC
BC=11.2
therefore value of BC is 11.2

Answer 2

Answer:

BC=1.07 cm

Step-by-step explanation:

Given two similar triangles ∆ ABC ~∆DEF and also their areas are respectively  $64 cm^{2} and \thinspace 121cm^{2}$. Also if one of the side i.e EF=15.4 cm then we have to find the side BC.

By similar triangle theorem

$\frac{Area(ABC)}{Area(DFE)}=\frac{BC^{2} }{EF^{2} }$

⇒$\frac{64}{121}=\frac{BC^{2} }{(15.4)^2}$

Taking square root on both sides, we get

⇒$\frac{8}{11}=\frac{BC}{3.92}$

⇒ BC=1.07 cm