FTCE General Knowledge Math Practice Test

Which formula calculates the perimeter of a rectangle?

1. LW

2. 2(L + W)

3. 1/2 bh

4. A + B + C

The correct answer is: 2(L + W)

The formula for calculating the perimeter of a rectangle is derived from the understanding that the perimeter is the total distance around the outside of the rectangle. A rectangle has two lengths (L) and two widths (W). Therefore, to find the perimeter, you need to add together the lengths of all four sides. The formula 2(L + W) accurately represents this total by adding the length and width together (which accounts for one of each dimension in the rectangle) and then multiplying the result by 2 to account for both pairs of sides. This ensures that both the lengths and widths are included in the final calculation, leading to the correct measure of distance around the rectangle. For context, the other formulas provided do not pertain to the perimeter of a rectangle. The formula LW represents the area of a rectangle, 1/2 bh refers to the area of a triangle, and A + B + C lacks specificity for a rectangle and does not denote a standard geometric formula. Thus, 2(L + W) is the only correct formula for finding the perimeter of a rectangle.