The lateral side of an isosceles triangle is twice its base. The perimeter of the triangle is 20 cm. Find the sides of the triangle.

An isosceles triangle has 2 sides, which are equal to each other and the base.

Let the base of the triangle be x cm, then the side is 2 * x cm.

The perimeter is the sum of all sides, we write the equation:

2 * x + 2 * x + x = 20;

we give similar terms on the left:

5 * x = 20;

x = 20: 5;

x = 4 cm – base.

4 * 2 = 8 cm – side.

Answer: the side is 8 cm, the base is 4 cm.