Answer :
Answer:
Maximum area = 10000 square units.
Step-by-step explanation:
We are given the following information:
Rectangular perimeter of coral = 400 units.
Let length of the coral be x. Then,
Perimeter = 400 = 2(Length +Breadth)
[tex]400 = 2(x + Breadth)\\Breadth = 200 - x[/tex]
Thus, the area of rectangle is given by,
[tex]Area = Length\times Breadth = x\times (200-x) = 200x - x^2[/tex]
Thus, we have to maximize the function:
[tex]f(x) = 200x - x^2[/tex]
We will use double derivative test.
First we differentiate with respect to x.
[tex]\displaystyle\frac{d(f(x))}{dx} = \displaystyle\frac{d(200x - x^2)}{dx} = 200 - 2x[/tex]
Equating this to zero to obtain critical points,
[tex]200 - 2x = 0\\200 = 2x\\x = 100[/tex]
Now, again differentiating with respect to x.
[tex]\displaystyle\frac{d^2(f(x))}{dx^2} = -2 < 0[/tex]
Thus, by double derivative test, local maxima occurs for this function at x = 100
So, Length = x = 100 units
Breadth = 200 - x = 100 units
Maximum area = 10000 square units.