(30 points!) The lengths of the sides of a triangle are in the extended ratio 4:7:9. The perimeter is 60cm. What are the lengths of the sides?

The lengths of the sides are 12cm, 28cm and 36cm.

Step-by-step explanation:

Let the smallest side be 4x, the middle side be 7x and the largest side be 9x.

Smallest side + middle side + largest side = 60cm

4x + 7x + 9x = 60

20x = 60

x = 60 ÷ 20

x = 3

Smallest side (4x) = 3 × 4

                             = 12

Middle side (7x)  = 7 × 4

                           = 28

Largest side (9x) = 9 × 4

                            = 36