Question

A Triangle ABC with AB=3cm BC=6cm AC=4cm is enlarged to a triangle DEF with longest side = 9cm.

Find the scale factor and hence the lengths of other sides of triangle DEF.

Answer 1

Largest side of triangle ABC is side BC = 6 cm

Let s be the scale factor

In trianlge DEF largest side will be equal to scale factor * Largest side of triangle ABC = s*6 cm = 6s cm

Larget side of triangle DEF = 9 cm

So 9 cm = 6s cm

s = 9/6 = 1.5

Scale factor = 1.5

Sides of triangle DEF are DE = s*AB , EF = s*BC , DF = s*AC

AB = 3 cm , BC = 6 cm , AC = 4cm

DE = 1.5*3 = 4.5 cm , EF = 1.5*6 cm = 9cm , AC = 1.5*4 = 6 cm

Sides of triangle DEF are 4.5cm , 9cm and 6cm