Let x and y be the dimensions of the rectangle. If the perimeter is 40, we have

We can expression one variable in terms of the others as

Since the area is the product of the dimensions, we have

This is a parabola facing down, so it's vertex is the maximum:

So, the maximum is

And since we know that
, we have
as well.
This is actually a well known theorem: out of all the rectangles with given perimeter, the one with the greatest area is the square.
Answer:
8
Step-by-step explanation:
(4+8)+6 = (6+4)+n
18 = 10+n
18-10 = n
n = 8
Answer:
The angle of rotation is 2.11 °
Step-by-step explanation:
Given as :
The radius of the round path = r = 18 feet
The length of the distance cover by wheel = l = 38 feet
Let The angle of rotation = Ф
Now, According to question
∵ length of the arc of a circle subtending an angle at center = Ф
So,
length of the distance cover by wheel = π × radius × 
Since 180° = π radian
And π = 3.14
So, length of the distance cover by wheel = 180 °× radius × 
i.e l = r × Ф
Or, Ф = 
Or, Ф = 
Or, Ф = 2.11 °
So, The angle of rotation = Ф = 2.11 °
Hence, The angle of rotation is 2.11 ° Answer
Answer:
B. A(r(t)) = 25πt²
Step-by-step explanation:
Find the completed question below
The radius of a circular pond is increasing at a constant rate, which can be modeled by the function r(t) = 5t where t is time in months. The area of the pond is modeled by the function A(r) = πr². The area of the pond with respect to time can be modeled by the composition . Which function represents the area with respect to time? A. B. C. D.
Given
A(t) = πr²
r(t) = 5t
We are to evaluate the composite expression A(r(t))
A(r(t)) = A(5t)
To get A(5t), we will replace r in A(t) with 5t and simplify as shown
A(5t) = π(5t)²
A(5t) = π(25t²)
A(5t) = 25πt²
A(r(t)) = 25πt²
Hence the composite expression A(r(t)) is 25πt²
Option B is correct.