The formula for calculating the perimeter of a triangle includes which variables?

The perimeter of a triangle is defined as the total length around the triangle, which is calculated by adding together the lengths of all three sides. This means that to find the perimeter accurately, you need to know the measurement of each side. Thus, the correct choice involves the lengths of all three sides of the triangle, ensuring that the entire perimeter is accounted for in the calculation.

Choosing only the length of the base ignores important information about the other two sides, which affects the total perimeter. Similarly, using just two sides or considering area and height does not provide a complete picture for calculating perimeter. Area and height pertain to different geometric properties and are not relevant to the perimeter measurement. Therefore, including all three side lengths is essential for an accurate calculation of the triangle's perimeter.