Question

Triangles ABC and DEF are similar.
If area (ΔABC) = 16 cm², area (ΔDEF) = 25 cm² and BC = 2·3 cm find EF.

Answer 1

We have
area (ΔABC) = 16 cm²
area (ΔDEF) = 25 cm²
and BC = 2·3 cm
Since , `"area (ΔABC)"/"area (ΔDEF)" = "BC"^2/"EF"^2`
⇒ `(16)/(25) = (2.3)^2/"EF"^2`
⇒ `(2·3)/"EF" = (4)/(5)`
⇒ 4EF = 5 x 2·3
⇒ EF = `(11.5)/(4)`
⇒ EF = 2·875 cm.