The lengths of the sides of a triangle are in the extened ratio 3:6:8. The triangle's perimeter is 520cm. What are the lengths of the sides?

The three lengths are 3x, 6x, 8x.

The perimeter of a triangle is the sum of all lengths:

3x + 6x + 8x = 520.

Solving for x,

17x = 520

x = 30.59 cm

So the three lengths are

3 (30.59) = 91.77 cm

6 (30.59) = 183.54 cm

8 (30.59) = 244.72 cm