Find the perimeter of triangle ABC with sides AB = 3 cm, BC = 6 cm, CA = 7 cm.

In the problem statement, we are given a triangle ABC and the length of each side is indicated. We need to find the perimeter of the given triangle. Let’s figure out what a perimeter is.
The perimeter of any geometric figure is equal to the sum of the lengths of its sides.
Thus, in order to find the perimeter of the triangle, we need to add all its sides. Let us denote the perimeter by the letter P.
P = AB + BC + CA = 3 + 6 + 7 = 16 cm.
Answer: the perimeter of triangle ABC is 16 cm.