2002 Winter Diet Calc. - Question 7 - help!
Posted 19 May 2005 - 09:25 AM
I know you'd do dS/dw and then find the maximum turning point but I can't get it to work out! And then finding d once you've got w... can anyone help?!
Posted 19 May 2005 - 11:15 AM
Posted 19 May 2005 - 11:43 AM
I ended up with w equalling 11.5 but it's wrong
Did you get dS/dw = 680 - 51.w2?
Posted 19 May 2005 - 12:02 PM
That is what I am getting....
Posted 19 May 2005 - 02:01 PM
You are right up to there. But it is W = 133.3333333333. So W = 133.3333333 = 11.55 to 2 dp.
Then sub into equation to find d? Edit: Maybe not, no d in the equation.
Surely the diameter must be inportant to this? Like to give the diagonals of the rectangle?
Posted 19 May 2005 - 02:03 PM
However, once it equals that, how do you find 'd'?
Posted 19 May 2005 - 02:08 PM
Posted 19 May 2005 - 02:20 PM
Posted 19 May 2005 - 02:24 PM
I went to extreme lengths, modelled the circle relative to the coordinates x,y, with a centre (0,0)
So produces an equation, x^2 + y^2 = 100
Then since you know the total length of w = 11.55, take half of this (5.775), and this is where it intersects with the circle. So it intersects at the point x = 5.775. Plug it into the circle equation and get the value for the y intersection coordinate. And then simply double this value to get the whole length. Again, it isn't in exact value form, but calculators were allowed.
Posted 19 May 2005 - 03:11 PM
Posted 19 May 2005 - 03:17 PM
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