The perimeter of an isosceles triangle is 39 cm, and the length of its lateral side is 3 cm longer

The perimeter of an isosceles triangle is 39 cm, and the length of its lateral side is 3 cm longer than the length of the base. Subtract the lengths of the sides of this triangle.

Given:
P = 39 cm;
The lateral side is 3 cm longer than the base.
Decision:
Let’s denote by x the length of each side. So, based on what is given in the condition, the base is x-3.
The perimeter is calculated by the formula: P = a + b + c.
Substitute our values and get: P = x + x + x-3.
Let’s write the value of P and find x.
39 = x + x + x-3
39 = 3x-3
3x = 39 + 3
3x = 42
x = 42/3 = 14.
So the sides of the triangle are 14 cm.
Find the base: x-3 = 14-3 = 11 cm.
Answer: 11, 14, 14