SOLUTION: John is building a pen in his backyard. the sides of the pen will form a right triangle with his home. the legs (base and height) of the triangle will be the pen material and the r

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Question 1157421: John is building a pen in his backyard. the sides of the pen will form a right triangle with his home. the legs (base and height) of the triangle will be the pen material and the remaining side (hypotenuse) will be formed by his home. in other words, he only needs fencing for the legs of the triangular region. you may assume the side of his home is as long as necessary. given that he only has 50 feet of material for the wall what is largest possible area of his backyard?
Answer by ikleyn(52890) About Me  (Show Source):
You can put this solution on YOUR website!
.

Let x and y be the sides (the legs) of this right angled triangle.


You have the total length of the legs given  x + y = 50  feet,

and you want maximize the area  A = %281%2F2%29%2Axy.


Express y = 50-x.

Then for the area, you have this formula

    A(x) = %281%2F2%29%2Ax%2A%2850-x%29 = -%281%2F2%29%2Ax%5E2 + 25x.


This quadratic function gets the maximum at  x = -25%2F%282%2A%28-%281%2F2%29%29%29 = 25%2F1 = 25 feet.


So, the optimum length for both legs is  x = 25 feet = y,


and the maximum area is  %281%2F2%29%2A25%2A25 = 625%2F2 = 312.5 square feet.

Solved.

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For closely related lessons, see
    - HOW TO complete the square to find the minimum/maximum of a quadratic function
    - Briefly on finding the minimum/maximum of a quadratic function
    - HOW TO complete the square to find the vertex of a parabola
    - Briefly on finding the vertex of a parabola

    - A rectangle with a given perimeter which has the maximal area is a square
    - A farmer planning to fence a rectangular garden to enclose the maximal area
    - A farmer planning to fence a rectangular area along the river to enclose the maximal area
    - A rancher planning to fence two adjacent rectangular corrals to enclose the maximal area
in this site.

Also,  you have this free of charge online textbook in ALGEBRA-I in this site
    - ALGEBRA-I - YOUR ONLINE TEXTBOOK.

The referred lessons are the part of this textbook under the topic "Finding minimum/maximum of quadratic functions".


Save the link to this online textbook together with its description

Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson

to your archive and use it when it is needed.