Which formula calculates the perimeter of a rectangle?

The formula that calculates the perimeter of a rectangle is indeed represented by the expression involving the addition of the rectangle's length and width, multiplied by two. This is because the perimeter is the total distance around the rectangle, which includes two lengths and two widths.

When you calculate the perimeter, you need to account for both pairs of opposite sides. The formula effectively sums the lengths of all four sides: two sides of length and two sides of width. In mathematical terms, it's expressed as:

Perimeter = Length + Length + Width + Width = 2 × Length + 2 × Width.

However, this can also be succinctly represented as 2 × (Length + Width), which ensures that you are taking into account both dimensions in a single operation. This representation highlights the relationship between the sides and reinforces the understanding that each dimension contributes equally to the overall boundary of the rectangle. Therefore, formula A is correct for determining the perimeter of a rectangle.