Rotating on a slant [repost]

[tlmerith]

Hi, I'm taking a summer Calculus course and my professor assigned the following take home assignment from Stewart.
http://www.stewartcalculus.com/data/CAL ... 02_stu.pdf
I'm having trouble finding the relationship between delta x and delta u. I've redrawn out a larger picture but I feel that my geometry knowledge isn't helping me out much. I think that it must have something to do with arctan since the final area formula begins with 1/(1+m^2). Beyond this I'm pretty lost. Any help would be appreciated.

I know (this) is such an old thread. But I need to have the answer to part 1 and 3
1. show that the area of R is…
3. Find a formula (similar to the one in Problem 1) for the volume of the solid obtained by rotating R about the line y=mx+b

I tried to follow along but I feel like a lot of people were including different parts at different time and I got very confused!

Thank you!

 

[stapel]

I know (this) is such an old thread. But I need to have the answer to part 1 and 3
1. show that the area of R is…
3. Find a formula (similar to the one in Problem 1) for the volume of the solid obtained by rotating R about the line y=mx+b

I tried to follow along but...I got very confused!

Please reply showing what you tried, how far you got, and where things ground to a halt. Thank you!