/sci/ - Science & Math » Thread #13416558

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Anonymous Tue 20 Jul 19:43:34 2021 No.13416558 View Reply Original Report

Quoted By: >>13416591 >>13416804 >>13416834 >>13416894 >>13417753 >>13417770 >>13417811 >>13418076 >>13418427 >>13418715 >>13418733 >>13421641 >>13422283 >>13422626

How would a brainlet begin this problem

Anonymous

Anonymous Tue 20 Jul 2021 19:47:08 No.13416576 Report

Quoted By: >>13416601

begin by drawing, long side for the barn and division is perpendicular to the barn etc

Anonymous

Anonymous Tue 20 Jul 2021 19:48:35 No.13416585 Report

Quoted By: >>13416627

dunno, I would care more about trying to get the gate positions right and how it connects into the rest of your handling system

Anonymous

Anonymous Tue 20 Jul 2021 19:50:11 No.13416591 Report

Quoted By: >>13416602 >>13417211

>>13416558
You haven't got the size of the barn so you can't.

Anonymous

Anonymous Tue 20 Jul 2021 19:52:16 No.13416601 Report

Quoted By: >>13416608 >>13416632

>>13416576
the idea is to make the sides the same value so

80+4(sqrt(80)

Anonymous

Anonymous Tue 20 Jul 2021 19:52:22 No.13416602 Report

Quoted By:

>>13416591
I assume It's a big barn of infinite size

Anonymous

Anonymous Tue 20 Jul 2021 19:53:31 No.13416608 Report

Quoted By: >>13416632

>>13416601
80 should be 800

Anonymous

Anonymous Tue 20 Jul 2021 19:58:07 No.13416627 Report

Quoted By:

>>13416585
I think you'd probably want deep pens maybe 5x12 with gates connecting gates near the outer side
it would give you more flexibility to shuffle stock between the three pens while keeping safe distance to work within and turn the livestock if necessary, for sheep you might want something even narrower.
if I ran out of fencing I might grab a few pallets to fill the gaps

Anonymous

Anonymous Tue 20 Jul 2021 19:59:53 No.13416632 Report

Quoted By:

>>13416601
>>13416608
i should explain
a square has the smallest side of area ratio of rectangles
so the idea is to make 2400 into 3 squares

so the answer is actually 7sqrt(800), i was wrong

Anonymous

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Anonymous Tue 20 Jul 2021 20:37:29 No.13416794 Report

Quoted By:

Are we using sheep hurdles?

Anonymous

Anonymous Tue 20 Jul 2021 20:39:24 No.13416804 Report

Quoted By: >>13416822

>>13416558
One side is a ft, the other two (a/2) ft.
Imagine a square with the side length a and area 4800 ft. The pen is the rectangle equal to half that square.

Anonymous

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Anonymous Tue 20 Jul 2021 20:46:18 No.13416819 Report

Quoted By: >>13416842

lets ask a better question which is the more useful orientation for ease of handling and sorting sheep between the pens?

my suggestion for a 15x12 divided into three pens of 5x12 with 4 swinging gates

Anonymous

Anonymous Tue 20 Jul 2021 20:46:41 No.13416822 Report

Quoted By:

>>13416804
Oh fuck. Didn't read that he wants to divide it in 3.
So the amount of fence should be 3a with
a^2 = 4800

Anonymous

Anonymous Tue 20 Jul 2021 20:50:30 No.13416834 Report

Quoted By:

>>13416558
Draw a picture, write an algebra equation, set derivative equal to zero.

Anonymous

Anonymous Tue 20 Jul 2021 20:52:13 No.13416842 Report

Quoted By: >>13416858

>>13416819
wait that's only 1800m^2? I meant for 800m^2 pens not 600m^2

Anonymous

Anonymous Tue 20 Jul 2021 20:56:55 No.13416858 Report

Quoted By:

>>13416842
so 16 metres deep instead of 12

Anonymous

Anonymous Tue 20 Jul 2021 21:08:47 No.13416894 Report

Quoted By:

>>13416558
Just by fucking doing it. Animal pens don't need exact dimensions.

Anonymous

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Anonymous Tue 20 Jul 2021 21:09:27 No.13416898 Report

Quoted By: >>13417339 >>13417975

How'd I do? This way the total length of fencing is the three sides of the pen.

Anonymous

Anonymous Tue 20 Jul 2021 22:57:06 No.13417211 Report

Quoted By:

>>13416591
Assume it is long enough for optimization

Anonymous

Anonymous Tue 20 Jul 2021 23:45:04 No.13417339 Report

Quoted By: >>13417352

>>13416898
The area of the barn isn't 2400 ft^2, the area of the pen is this.

This is an optimization question with the constraint equation l.w = 2400 ft^2 and the optimization equation as P = 4l + w (if you assign w as the width for the side parallel to the barn, and l as the length/side perpendicular to the barn). Use substitution from area equation and then set derivative of P equal to 0, solve.

Anonymous

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Anonymous Tue 20 Jul 2021 23:49:30 No.13417352 Report

Quoted By:

>>13417339

Anonymous

Anonymous Wed 21 Jul 2021 02:13:17 No.13417753 Report

Quoted By:

>>13416558
>divides the pen into three sections
Three equal sections, presumably? There's no least amount of fencing if the three sections don't have to be equal, though there is a limit.

Anonymous

Anonymous Wed 21 Jul 2021 02:22:51 No.13417770 Report

Quoted By:

>>13416558
By asking the internet apparently

Anonymous

Anonymous Wed 21 Jul 2021 02:37:51 No.13417811 Report

Quoted By: >>13417969

>>13416558
x: Length of barn side
y: Length of non-barn side
z: Length of fence

x*y = 2400
z = 2y + x
-> z = 2y + 2400/y
-> dz/dy = 2 - 2400/y^2
-> 0 = 2 - 2400/y^2
So
y = 20*sqrt(3)
x = 40*sqrt(3)

The min amount of fencing needed is:
2*20*sqrt(3) + 40*sqrt(3) = 80*sqrt(3) = 138.56... feet

FUCK /POL/ TOURISTS

FUCK /POL/ TOURISTS Wed 21 Jul 2021 03:23:15 No.13417923 Report

Quoted By: >>13417936 >>13418271

Assuming three equal sections (otherwise the internal
fencing can become arbitrarily small), and assuming,
without loss of generality, that l >= w:

A = lw = 2400

CASE 1: Barn on the length (l)

F = 4w + l
F = 4w + 2400w^(-1)
F'= 4 - 2400w^(-2)

4 - 2400w^(-2) = 0
4w^2 = 2400
w = sqrt(600)

min(F) = 4sqrt(600) + 2400/sqrt(600) = ~196

CASE 2: Barn on the width (w)

F = 2w + 3l
F = 2w + 7200w^(-1)
F' = 2 - 7200w^(-2)

2 - 7200w^(-2) = 0
2w^2 = 7200
w = 60

min(F) = 2(60) + 7200/60 = 240

Anonymous

Anonymous Wed 21 Jul 2021 03:30:34 No.13417936 Report

Quoted By: >>13417958 >>13417962

>>13417923
This is wrong

Anonymous

Anonymous Wed 21 Jul 2021 03:40:11 No.13417958 Report

Quoted By: >>13417969 >>13417975

>>13417936
Prove it.

FUCK /POL/ TOURISTS

FUCK /POL/ TOURISTS Wed 21 Jul 2021 03:41:34 No.13417962 Report

Quoted By: >>13417969

>>13417936
What a brilliant post.

Anonymous

Anonymous Wed 21 Jul 2021 03:46:20 No.13417969 Report

Quoted By: >>13418067

>>13417958
>>13417962
This guy proved it 1 post above you
>>13417811

Anonymous

Anonymous Wed 21 Jul 2021 03:48:52 No.13417975 Report

Quoted By: >>13418067 >>13418196

>>13417958
you can get a lower amount of fencing just by trying out different shapes. even my dumbass idea to make 3 equal square pens takes ~40' less fencing than your answer, and 3 20x40 rectangles takes 40' less than 3 squares, but really >>13416898 has it right because the problem doesn't state that the three sections have to be equal size

Anonymous

Anonymous Wed 21 Jul 2021 03:55:58 No.13417997 Report

Quoted By:

For three sections of equal size the minimum length of fence you need is about 195.96 feet.

FUCK /POL/ TOURISTS

FUCK /POL/ TOURISTS Wed 21 Jul 2021 04:23:54 No.13418067 Report

Quoted By: >>13418104

>>13417969
He didn't include any internal fencing.
>>13417975
>even my dumbass idea to make 3 equal square pens takes ~40' less fencing than your answer, and 3 20x40 rectangles takes 40' less than 3 squares
Where can I find your full math?
>the problem doesn't state that the three sections have to be equal size
I stated it right there in my post: "assuming three equal sections (otherwise the internal fencing can become arbitrarily small)."

Anonymous

Anonymous Wed 21 Jul 2021 04:27:33 No.13418076 Report

Quoted By:

>>13416558
How long is the barn along the side you plan on building the fence? That effects this problem and everyone in this thread has been ignoring it. This is a poorly defined problem. It Doesn't even contain all pertinent information.

Anonymous

Anonymous Wed 21 Jul 2021 04:36:24 No.13418104 Report

Quoted By: >>13418126

>>13418067
>He didn't include any internal fencing.
Yeah you're right I'm a retard

FUCK /POL/ TOURISTS

FUCK /POL/ TOURISTS Wed 21 Jul 2021 04:44:44 No.13418126 Report

Quoted By:

>>13418104
I wasn't saying you were wrong. Different assumptions. My numbers are assuming three equal sections (as I stated), so I need internal fencing. The wording of the question allows one to make a different assumption -- unequal sections -- in which case your approach is correct to find a limit.

FUCK /POL/ TOURISTS

FUCK /POL/ TOURISTS Wed 21 Jul 2021 05:09:21 No.13418196 Report

Quoted By:

>>13417975
>and 3 20x40 rectangles
It's possible I've done something retarded, but if so, it's in F = 4w + l in CASE 1 and/or F = 2w + 3l in CASE 2, because I'm certain that the calculations that follow are correct. I think you may have overlooked that I had two minimums, ~196 and 240.

The best I can do with your numbers is to have a 20x120 pen with a barn knocking out one of the 120 lengths.
This corresponds to my CASE 1.
20 + 20 + 20 + 20 + 120 = 200
That's ~4 more feet of fencing than my ~196 for CASE 1.

Anonymous

Anonymous Wed 21 Jul 2021 05:35:36 No.13418271 Report

Quoted By: >>13418274 >>13421774 >>13422308 >>13423778

>>13417923
>F = 4w + 2400w^(-1)
>F'= 4 - 2400w^(-2)
this isn't even how agebra works, you dumb nigger. if you divide thru by w, you don't change the sign before 2400

Anonymous

Anonymous Wed 21 Jul 2021 05:37:21 No.13418274 Report

Quoted By: >>13418386 >>13423778

>>13418271
>divide
OH NO NO NO

Anonymous

Anonymous Wed 21 Jul 2021 06:20:35 No.13418386 Report

Quoted By: >>13422308 >>13423778

>>13418274
4w --> /w --> 4
+ 2400w^(-1) ---> /w --> + 2400w^(-2)
sign dont change

Anonymous

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Anonymous Wed 21 Jul 2021 06:53:44 No.13418427 Report

Quoted By:

>>13416558
the standard issue contemporary brainlet would start out by mocking the farmer for being a dumb redneck from flyover country

Anonymous

Anonymous Wed 21 Jul 2021 09:01:05 No.13418715 Report

Quoted By: >>13418719

>>13416558
>x*y = 2400
>minimise x + 2y
>minimise x + 4800/x
>A.P. >= G.P.

Anonymous

Anonymous Wed 21 Jul 2021 09:02:39 No.13418719 Report

Quoted By: >>13418724

>>13418715
This is wrong, doesn’t take into account the division into 3 sections.

Anonymous

Anonymous Wed 21 Jul 2021 09:05:41 No.13418724 Report

Quoted By:

>>13418719
The correction would be
>x*y = 2400
>minimise x + 2y + 2*min(x, y)

Anonymous

Anonymous Wed 21 Jul 2021 09:10:20 No.13418733 Report

Quoted By:

>>13416558
Are the 3 sections supposed to be equal or something? Because you see, if we take the limit of the area of 2 sections to approach 0, you can just build a big square with an area of 2400 square feet. Well, assuming the side of the barn is also equal to or greater than one of the sides of that square. How big is the barn again?

Anonymous

Anonymous Wed 21 Jul 2021 22:36:17 No.13421256 Report

Quoted By:

It says nowhere that the sections have to be rectangular

Anonymous

Anonymous Thu 22 Jul 2021 01:04:25 No.13421641 Report

Quoted By:

>>13416558
one begins and ends the problem by knowing the fact that the shape enclosing the maximum area for a given perimeter is a circle
you can prove that using calculus of variations, but don't bother and just learn this popular, simple, and almost self-evident fact

Anonymous

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Anonymous Thu 22 Jul 2021 02:02:07 No.13421774 Report

Quoted By: >>13423778

>>13418271
The absolute state of Dunning–Kruger /sci/.

Anonymous

Anonymous Thu 22 Jul 2021 05:32:51 No.13422283 Report

Quoted By:

>>13416558
divide 2400 by 3. That the length of each side.

Anonymous

Anonymous Thu 22 Jul 2021 05:46:42 No.13422308 Report

Quoted By: >>13423778

>>13418271
>>13418386
Sorry, but I just can't stop laughing at this. It captures /polsci/ perfectly.

Anonymous

Anonymous Thu 22 Jul 2021 08:33:46 No.13422626 Report

Quoted By:

>>13416558
>How would a brainlet
He wouldn't.

Anonymous

Anonymous Thu 22 Jul 2021 16:50:27 No.13423778 Report

Quoted By:

>>13418271
>>13418274
>>13418386
>>13421774
>>13422308
This has to be bait, right? Do /pol/fags really this stupid???

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