# Help with maths question (pure)

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#1

(a) I am confused by "length of the track is 300m) do they mean the perimeter?
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2 years ago
#2
Yes, i'd assume they mean the perimeter of the entire shape
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#3
Now my question is why do you differentiate to find value of r in part b.What does differentiation tell us?
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2 years ago
#4
(Original post by Anonymous1502)
Now my question is why do you differentiate to find value of r in part b.What does differentiation tell us?
Anytime it asks you to find a maximum value you can assume you're going to have to differentiate, this is because you can model the equation with a graph and differentiate it to find the turning point (in this case the maximum value is the one you want).
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#5
(Original post by Maxiimoose)
Anytime it asks you to find a maximum value you can assume you're going to have to differentiate, this is because you can model the equation with a graph and differentiate it to find the turning point (in this case the maximum value is the one you want).
Thnak you.So differentiation shows us the maximum point?I always thought differentiation shows a small change in y /x of a curve so you get a more accurate gradient which is closer to the true value.
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2 years ago
#6
(Original post by Anonymous1502)
Thnak you.So differentiation shows us the maximum point?I always thought differentiation shows a small change in y /x of a curve so you get a more accurate gradient which is closer to the true value.
uhm, well differentiation is the gradient function of the curve, finding the turning point requires integrating and finding the value for which d/dx = 0, to find the nature of this point, you need to differentiate again to get the 2nd derivative (d2y/dx^2) and you'll find it's less than 0 for a maximum point.
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