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#1 2011-03-11 22:06:12

Kryptonis
Member
Registered: 2011-03-03
Posts: 11

Length of a curve

x = t / (3+t) y = ln(3 + t) 0 ≤ t ≤ 4

Here's the problem, my real question lies in the answer...

-sqrt(u^2 + 9)/(u) + ln(u + sqrt(u^2 + 9)) with the lower @ 3 and the upper @ 7
where u = t + 3 and du = dt

When I integrate, I'm at a loss as to how i should be coming up with -sqrt(u^2 + 9)/(u) + ln(u + sqrt(u^2 + 9)).
As I keep coming up with -sqrt(u^2 + 9)/(u) + ln(sqrt(u^2 + 9).

Last edited by Kryptonis (2011-03-11 22:07:55)

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#2 2011-03-11 23:58:30

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Length of a curve

Hi;

Did you start off like this?


Then did you use this formula?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#3 2011-03-12 13:18:51

soroban
Member
Registered: 2007-03-09
Posts: 452

Re: Length of a curve

. . . . . . . . . . .

. . I'll let you verify my trig identities.



.

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