# The perimeter of the triangle is 186mm, the length of one side is 42mm, the second side is 2

**The perimeter of the triangle is 186mm, the length of one side is 42mm, the second side is 2 times longer from it. Why exactly the third side of the triangle.**

Let us determine the length of the second side of the indicated triangle, knowing by the condition of the problem that it is 2 times greater than the length of the first side of the triangle:

42 * 2 = 84.

Let’s determine what the sum of the lengths of the first and second sides of the specified triangle is equal to:

42 + 84 = 126.

Let us determine the length of the third side of this triangle, knowing by the condition of the problem that the perimeter of this triangle is equal to 186 millimeters:

186 – 126 = 60.

Answer: The length of the third side of the indicated triangle is 60 millimeters.