If ΔABC∼ΔQRP,ar(ΔABC)ar(ΔPQR)=94, AB = 18 cm and BC = 15cm, then PR is equal to
(A) 10 cm
(B) 12 cm
(C) 203cm
(D) 8cm
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Solution
(A) 10 cm
Given, in ΔABC∼ΔQRP,AB=18cmandBC=15cm
We know that, the ratio of area of two similar triangles is equal to the ratio of square of their corresponding sides. ∴ar(ΔABC)ar(ΔQRP)=(BC)2(RP)2
But given, ar(ΔABC)ar(ΔPQR)=94 [given] ⇒(15)2(RP)2=94 [∵ BC=15cm, given] ⇒(RP)2=225×49=100 ∴RP=10cm