What is the formula to find the perimeter of a triangle?

The perimeter of a triangle is calculated by adding the lengths of all three sides. This summation gives the total distance around the triangle, which is why the correct answer involves taking the sum of all three sides. Each side contributes to the overall boundary of the shape, making it essential to include them all in the calculation.

For example, if a triangle has side lengths of 3 cm, 4 cm, and 5 cm, the perimeter would be 3 + 4 + 5, resulting in 12 cm. This straightforward method applies to triangles of any type—equilateral, isosceles, or scalene—demonstrating its universal applicability in geometry. Understanding this formula is fundamental for students, as it lays the groundwork for more complex concepts in both geometry and overall mathematical reasoning.