Question

Question 2. ∆ABC ~ ∆DEF. If AB = 4 cm, BC = 3.5 cm, CA = 2.5 cm and DF = 7.5 cm, find the perimeter of ∆DEF.

Answer 1

Because triangle ABC ∼ triangle DEF

∴ perimeter of triangle ABC : perimeter of triangle DEF = AC : DF

Perimeter of triangle ABC = 4+3.5+2.5 = 10cm

10 : perimeter of triangle DEF = 2.5 : 7.5

Cross multiplying

Perimeter of triangle DEF = 10× 7.5/2.5

∴ perimeter of triangle DEF = 30cm