# The perimeter of the triangle is 28 cm. The lengths of the first and second sides are 9 cm

**The perimeter of the triangle is 28 cm. The lengths of the first and second sides are 9 cm and 7 cm. Find out the length of the third side of the triangle.**

The solution of the problem:

The task is not difficult. To answer the question of the problem, you need to know the sum of the two sides of the triangle. From the condition of the problem, the length of one side of the triangle is known and the length of the second side of the triangle is known.

1. Find out what the sum of the length of the first side of the triangle and the length of the second side of the triangle is equal to.

9 + 7 = 16 centimeters.

Let’s answer the question of the problem.

2. Find out what is the length of the third side of the triangle.

28-16 = 12 centimeters.

Answer: The length of the third side of the triangle is twelve centimeters.