Answer:
Length = Width = 55
Explanation:
Perimeter of rectangle = 2(length + width)
Let x = length; let y = width.
perimeter = 2(x + y)
The perimeter must be 220.
2(x + y) = 220
x + y = 110
y = 110 - x
length = x
width = 110 - x
area = length × width
area = x(110 - x)
area = 110x - x²
A = 110x - x²
Take the first derivative of the area function and set equal to zero. Then solve for x.
A' = 110 - 2x
110 - 2x = 0
2x = 110
x = 55
y = 110 - x = 110 - 55 = 55
Answer: Length = Width = 55