Max is building a rectangular dog pen. One side of the pen will just be the side of the house. If he has 45 feet of fencing to use for the other three sides,
Mathematics
miya110399
Question
Max is building a rectangular dog pen. One side of the pen will just be the side of the house. If he has 45 feet of fencing to use for the other three sides, what is the largest area he can create? Round to the nearest tenth.
1 Answer

1. User Answers Anonym
let the shorter sides of the rectangle be x feet
then the length of the 3 sides will be x , x and 45  2x
The area of the rectangle will be x(452x) = 45x  2x^2
we need to find the maximum value of this area
Find the derivative:
A' = 45  4x = 0 for a maximum values
4x = 45
x = 45/4 = 11.25
So maximum area = 11.25(45  22.5) = 253.1 square feet