Question

let∆abc ~∆def and their areas be respectively 64cm square and 121 cm square if EF=15.4cm.find bc

Answer 1

Answer:

as

Ar triangle abc/area of triangle def=ab/de*=bc/ef*=ac/df*

Are triangle abc/area of triangle def=bc/ef*

64/121=bc/1.54*

Taking square roots on both sides we get,

Root 64/121=bc/15.4

8/11multipy by15.4=bc

Bc=11.2cm

Step-by-step explanation:

Answer 2

$\bf\huge\underline{Question}$

Let ∆ABC ~∆DEF and their areas be respectively 64 cm square and 121 cm square if EF=15.4cm, find BC.

$\bf\huge\underline{Solution}$

We have ar(∆ABC) = 64 cm²

ar(∆DEF) = 121 cm² and EF = 15.4 cm [Given]

Since, ∆ABC ~ ∆DEF

Therefore, $\dfrac{ar(traingleABC)}{ar(traingleDEF)}$ = $\dfrac{(BC)}{(EF)}$

[Ratios of areas of two similar traingles is equal to the ratio of the squares of their corresponding sides.]

=> $\dfrac{64}{121}$ = $\dfrac{BCsquare}{(15.4)square}$

=> $\dfrac{8}{11}$ = $\dfrac{BC}{15.4}$

=> BC = $\dfrac{8 × 15.4}{11}$ = 11.2 cm

Thus, BC = 11.2 cm