A triangle has two sides of the same length. The perimeter of the triangle is 16 cm, and the third side is 4 cm.

A triangle has two sides of the same length. The perimeter of the triangle is 16 cm, and the third side is 4 cm. What is the length of the first and second sides of the triangle.

Let’s find the sum of the two sides of the triangle, because the third side is known. To do this, subtract the third side from the perimeter of the triangle:

1) 16 – 4 = 12 (cm) – the sum of the two sides of the triangle;

It is known that the other two sides are the same, so the result obtained, that is, the sum of the two sides, must be halved. Thus, we get the lengths of two identical sides of the triangle.

2) 12: 2 = 6 (cm) – the length of the two sides of the triangle.

Answer: 6 cm each is the length of the first and second sides of the triangle.