Triangle ABC AB 27cm BC is 3 times larger than the length of AC if the perimeter of the triangle is 61cm.

As you know, the perimeter of a geometric figure is the sum of the lengths of all its sides. Since triangle ABC has three sides, therefore the perimeter can be found as:

AB + BC + CA.

Since it is known from the condition of the problem that the length of the BC side is 3 times less than the length of the AB side, therefore:

BC = AB / 3 = 27/3 = 9 cm.

Let’s find the sum of the sides BC and AB:

9 + 27 = 36 cm.

Now, since the perimeter of the triangle is known, we find the length of the third side:

61 – 36 = 25 cm.

Answer: 25 cm.