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Ralfskini
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#21
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#21
Nor can u with an equilateral triangle- i didnt mention rectangles.
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Elle
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#22
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#22
(Original post by Toffee)
Since when are there women farmers?
Woohoo! At least that something the exam boards have got right!
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theone
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#23
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#23
But we can hardly consider just regular shapes with equal sides.
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Ralfskini
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#24
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#24
(Original post by theone)
Well this is only true when the perimeter fixes all other parameters.
I know- like in the case of an equilateral triangle, circle and square which is what i said! Of course it doesnt for a rectangle, isosceles triangle, etc.......
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PQ
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#25
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#25
(Original post by Ralfskini)
I know- like in the case of an equilateral triangle, circle and square which is what i said! Of course it doesnt for a rectangle, isosceles triangle, etc.......
But using the idea that to solve problems like this you start with the simple things and gradually introduce more and more complexity it would make sense to consider the area of regular sided shapes first and then move on to varying the lengths of each side...and in the case of the specific question asked (which shape would produce the largest area with a fixed perimeter it would lead progressivly to the correct answer - a circle).
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leeds_lad_luke
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#26
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#26
rite im doin the same as the fencing coursework but its guttering, i have been asked to apply the calculus method to get an a* in the coursework, i kinda know how to do the actual coursework itself but i dont understand what calculus does... ne help?
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idiopathic
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#27
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#27
wow calculus @ gcse? the only gcse students who'd know any calculus are those in amazing private schools, in which case he wouldn't need help. so better to keep it simple!
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4Ed
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#28
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(Original post by leeds_lad_luke)
rite im doin the same as the fencing coursework but its guttering, i have been asked to apply the calculus method to get an a* in the coursework, i kinda know how to do the actual coursework itself but i dont understand what calculus does... ne help?
well if u read the 2nd post, theone does a pretty good job of explaining calculus in a fairly convincing way (for a rectangle).

In this case for ur fencing/guttering problem, u are investigating how the area changes as the variable x (which changes the dimensions of your polygon) changes. If you plot a graph of dimension against area, it will follow some function (eg a quadratic of ax^2 + bx + c). The calculus that theone is doing here is called Differentiation, where u investigate at what point on the graph the area is at a maximum/minimum/turning point (using the techniques he mentioned above). this is an exact way of calculating what dimensions for ur polygon (a square in the aforementioned post) is needed for a maximum area.

hope that helps.
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meepmeep
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#29
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#29
(Original post by _Devour_You)
wow calculus @ gcse? the only gcse students who'd know any calculus are those in amazing private schools, in which case he wouldn't need help. so better to keep it simple!
I did a tiny bit of calculus for the Fencing Problem and I'm just a comp kid. Had to look it up in a text book though. Basically, you'll only be able to do it for a general formula with a form like x^3+2x^2+x+3 and not things like (x^4+1)/(x^2) because they are more complicated and you can just say that this is beyond the scope of this piece of coursework. Doing some basic calculus will give you the 8 in the final strand though (although I think it's definately possible to get it without calculus, it makes it considerably easier to show that the maximum has been reached by finding the point where the gradient is zero and it is decreasing, hence giving a local maxima)
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