Question

Consider   ABC DEF ~ and their areas are respectively 64cm2

and 121 cm2

. If EF = 15.4 cm,

then find BC.​

Answer 1

Answer:

∆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

Step-by-step explanation:

By similar triangle theorem:

\frac{Area(ABC)}{Area(DFE)}=\frac{BC^{2} }{EF^{2} }Area(DFE)Area(ABC)=EF2BC2

⇒\frac{64}{121}=\frac{BC^{2} }{(15.4)^2}12164=(15.4)2BC2

Taking square root on both sides, we get

⇒\frac{8}{11}=\frac{BC}{3.92}118=3.92BC

⇒ BC=1.07 cm