Final answer:
The formula P = 2L + 2W calculates the perimeter of a rectangle, where L is the rectangle's length and W is its width. This is comparable to calculating the perimeter of a square, which is 4a, with 'a' being the side of the square.
Step-by-step explanation:
The formula P = 2L + 2W is used when calculating the perimeter of a rectangle. This formula arises from the fact that a rectangle has two pairs of equal sides, making the total perimeter the sum of twice the length (2L) and twice the width (2W). This is analogous to the way the perimeter of a square is calculated, which is 4 times the length of one side (4a), since all sides are equal. Using units of measure can help ensure the formula's correctness - perimeter is a linear measurement and will have units of length, while the area would be in square units, such as square meters (m²).
When trying to remember geometric formulas, it can be helpful to think about simple shapes like squares and relate them to more complex shapes. For example, the perimeter of a circle is known as the circumference and is calculated with the formula C = 2лr, while the area of a circle is A = лr². Similarly, for a rectangle, one can easily remember that the perimeter involves adding lengths of sides, while the area would involve multiplying the length and width (A = L × W).