Verified answer

Step-by-step explanation:

Let x be the length of the third side of the isosceles triangle.

Since the other two sides are twice as large as the third side, each of them has a length of 2x.

The perimeter of the triangle is the sum of the lengths of all three sides, so we have:

x + 2x + 2x = 30

Simplifying and solving for x, we get:

5x = 30

x = 6

Therefore, the length of each of the equal sides of the isosceles triangle is:

2x = 2(6) = 12

And the length of the third side is:

x = 6

So the sides of the triangle are 12 cm, 12 cm, and 6 cm.