What formula calculates the area of a rectangle?

The area of a rectangle is determined by multiplying its length by its width. This calculation arises from the definition of area, which represents the total space contained within the boundaries of the rectangle. By multiplying the length (the longer side) by the width (the shorter side), you account for all the unit squares that fit within the rectangle.

In contrast to the correct formula, the other options do not represent the correct way to calculate area. For instance, adding the length and width only gives you a perimeter measure rather than a measure of the space contained. Using width squared or length squared incorrectly assumes the shape is square, thus failing for rectangles where the two dimensions can vary independently. Hence, the multiplication of length and width is the only formula that accurately calculates the area of a rectangle.