- #1

fanttamdiv

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## Homework Statement

This isn't for homework but the question fits the general HW format. Basically, I am getting a different answer from my colleague on the double integral below so I am trying to find out why. I am trying to put this into excel so I can play with the numbers and see the different results. The double integral is attached (Image upload wasn't working, hopefully this isn't a big deal).

## Homework Equations

The values I am using are as follows:

a: 2

b:1.2

c:1

## The Attempt at a Solution

So the first integration (with respect to y) yields me this:

(.5)*(((x^2)*(arsinh((sqrt((a^2)-(x^2)))/x)))-(b*(sqrt((x^2)+(b^2))))+(a*(sqrt((a^2)-(x^2))))-((x^2)*(arsinh(b/x))))

Remember, I am putting this through excel so I am keeping the variables in there until the end. The second integration (with respect to x now) yields me this:

.5*(((-b^3)*(arsinh(c/b)))+((a^3)*(arcsin(c/a)))-((b*c)*(sqrt((c^2)+(b^2))))+((a*c)*(sqrt((a^2)-(c^2)))))

So now that I have this, I can have excel plug in the variables listed in the above section and get the answer. With the variables above, I am getting

**~2.234**. My colleague, however, is getting

**~2.361**. I do not have access to his work, and he seems confident in his answer. Basically I am bringing up this issue a couple years after he did the original problems and he isn't allotted any more time to work on this so I'm on my own. Is there something I am doing wrong?

Thanks

#### Attachments

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