1. The problem statement, all variables and given/known data i'm having trouble with these solid of revolution problems because a lot of them require you to find "length of the segment" before evaluating the problem. example: a solid lies between planes perpendicular to x=-5 and x=5. the cross section in the xy plane is the ellipse ((x2)/25)+((y2)/36)=1. 2. Relevant equations find L=f(x) 3. The attempt at a solution does that mean i mean i have to make the given equation a function of x? because when i attempt that, it does not turn out to be correct. according to the example this is the correct result, L=(12/5)√(25-x2) how can i arrive at that result? thank you in advance. by the way, i am posting from my ipad so if the format of the question is not correct, i apologize.