Minimum cost of an area of fencing using derivatives

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SUMMARY

The discussion revolves around optimizing the dimensions of a rectangular garden to minimize the homeowner's fencing costs while maintaining an area of 432 m². The homeowner shares a fence with a neighbor, who will cover half the cost of the shared side. The optimal dimensions of the garden must be calculated using principles of calculus, specifically derivatives, to minimize the total cost of fencing at $45/m. The conversation emphasizes the importance of clarity in problem statements and encourages practice to build confidence in solving such optimization problems.

PREREQUISITES
  • Understanding of calculus, specifically derivatives and optimization techniques
  • Familiarity with area calculations for rectangles
  • Basic knowledge of cost analysis in construction or fencing
  • Ability to interpret and clarify mathematical problem statements
NEXT STEPS
  • Study optimization problems using derivatives in calculus
  • Learn how to set up and solve area and perimeter equations for rectangles
  • Explore cost minimization techniques in real-world applications
  • Review effective communication strategies for presenting mathematical solutions
USEFUL FOR

Students studying calculus, particularly those focusing on optimization problems, as well as educators looking for examples of real-world applications of derivatives in cost analysis.

Physics345
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Homework Statement


A homeowner wishes to enclose a rectangular garden with fencing. The garden will be adjacent to his neighbour’s lot. There will be fencing on all four sides. His neighbour will be paying for half the shared fence.

a) What should the dimensions of the garden be if the area is 432 m^2 and the homeowner would like to keep his share of the cost to a minimum? Include a diagram.

b) At $45/m, what is the homeowner’s cost? What is the neighbor's cost?

Homework Equations

The Attempt at a Solution


For this question my main issue is the wording in the question I'm not sure exactly what it wants. Does it want me to find the homeowner/neighbors individual dimensions, or the dimensions of the whole garden.
Anyways here's what I've done so far let me know what you guys think.
Also on a side note, I wrote a whole bunch of stuff out on word, to ask about, so I'm just posting all of them at once on different threads (In case anyone was wondering about the multiple threads I just posted)

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As I said in your other thread, your answer is hard to follow. It would help a lot if you typed your answer directly, see https://www.physicsforums.com/help/latexhelp/

Physics345 said:
For this question my main issue is the wording in the question I'm not sure exactly what it wants. Does it want me to find the homeowner/neighbors individual dimensions, or the dimensions of the whole garden.
I think that the problem is quite clear: "What should the dimensions of the garden be?" The answer should be the dimensions of the sides of the rectangle, with a specification as to which side is adjacent with the neighbour.

Your answer is correct.
 
I need to stop doubting my self when I'm relatively sure the answer is correct. The doubt will go away with more practice hopefully.
Once again thank you!
 
Thread moved. @Physics345, please post questions that involve derivatives in the Calculus & Beyond section, not in the Precalc section.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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