∆ABC is similar to ∆DEF, and the ratio of the area of triangle ABC to triangle DEF is 25 ∶ 144. If AB = p cm, AC = q cm, and BC = r cm, then DE =?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. .
(Area of ∆ABC)/(Area of ∆DEF) = 25/144
⇒ (AB/DE)2 = (AC/DF)2 = (BC/EF)2 = 25/144
⇒ AB/DE = AC/DF = BC/EF = 5/12
AB = p
So, p/DE = 5/12
⇒ DE = (12p)/5
⇒ DE = (12/5)p
Therefore, the value of DE is (12/5)p.