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Question
∆ABC ∼ ∆DEF, ar(∆ABC) = 9 cm2, ar(∆DEF) = 16 cm2. If BC = 2.1 cm, then the measure of EF is
Options
2.8 cm
4.2 cm
2.5 cm
4.1 cm
Solution
Given: `Ar(Δ ABC)=9cm^2,AR(Δ DEF)=16 cm^2` and `BC= 2.1 cm`
To find: measure of EF
We know that the ratio of areas of two similar triangles is equal to the ratio of squares of their corresponding sides.
`(Ar(Δ ABC))/(Ar(Δ DEF))=(BC)^2/(EF)^2`
`9/16=(2.1)^2/(EF)^2`
`3/4=2.1/(EF)`
`EF=2.8 cm`
Hence the correct answer is `a`
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