SOLUTION: What is the minimum amount of fencing needed to construct a rectangular enclosure containing 1800 square feet using a river as a natural boundary on one side?

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Question 1093825: What is the minimum amount of fencing needed to construct a rectangular enclosure containing 1800 square feet using a river as a natural boundary on one side?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
What is the minimum amount of fencing needed to construct a rectangular enclosure containing 1800 square feet using a river as a natural boundary on one side?
:
let L = the length
let w = the width
:
Area
L * w = 1800
L = 1800%2Fw
:
perimeter (p), only 3 sides of fence required, therefore
p = L + 2w
Replace L with 1800%2Fw
p(w) = 1800%2Fw + 2w
:
Plot this equation
+graph%28+300%2C+200%2C+-50%2C+150%2C+-50%2C+200%2C+%281800%2Fx%29%2B2x%2C+120%29+
minimum fencing occurs when w = 30, then L = 1800/60 = 60
therefore min fencing is 120 (green line). 60 + 2(30)