The perimeter of a triangle in which one side is 15 cm and the other 13 cm is 45 cm, find its third side.

The perimeter of a triangle is equal to the sum of its three sides. From the condition of the problem, the length of the two sides of the triangle is known, and it is also known what the perimeter of the triangle is. Let’s answer the question of the problem.
Let’s calculate what is the length of the third side of the triangle.
45 – (15 + 13) = 45 – 28 = 17 centimeters.
Answer: The third side of the triangle is seventeen centimeters.