Find the lengths of the sides of an isosceles triangle if one of them is 3cm longer than the other, and the perimeter is 12cm.

1. Let’s denote the base of an isosceles triangle through x cm.

2. Determine what the lateral side of an isosceles triangle will be equal to:

(x + 3) cm.

3. Let’s compose and solve the equation.

2 * (x + 3) + x = 12;

2 * x + 2 * 3 + x = 12;

2x + 6 + x = 12;

3x + 6 = 12;

3x = 12 – 6;

3x = 6;

x = 6: 3;

x = 2.

4. The base of an isosceles triangle is x = 2 cm.

5. What is the side of the triangle?

x + 3 = 2 + 3 = 5 cm.

Answer: the sides of an isosceles triangle are 2 cm, 5 cm, 5 cm.