Question

∆ABC ∼ ∆PQR such that ar(∆ABC) = 4 ar(∆PQR). If BC = 12 cm, then QR =

पर्याय

• 9 cm

• 10 cm

• 6 cm

• 8 cm

Answer 1

Given: In Δ ABC and ΔPQR

`Δ ABC ∼ Δ PQR`

`Ar (Δ ABC) = 4Ar (Δ PQR)`

`BC=12 cm`

To find: Measure of QR

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 PQR))=(BC)^2/(QR)^2`

`(4Ar(Δ  ABC))/(Ar(Δ PQR))=12^2/(QR^2)`(Give Ar(Δ ABC)=4Ar (Δ PQR))

`4/1=12^2/(QR^2)`

`2/1=12/(QR)`

Hence the correct answer is `c`