integral question

*To*: mathgroup at smc.vnet.net*Subject*: [mg49834] integral question*From*: "quest04" <na at na.na>*Date*: Tue, 3 Aug 2004 01:11:06 -0400 (EDT)*Reply-to*: "quest04" <na at na.na>*Sender*: owner-wri-mathgroup at wolfram.com

Hello, I have a question and was wondering if someone could help me with it. This is a general vector calculus problem, not specific to Mathematica. I have a simple integral as follows: Given r^2= x^2+y^2, solve Integral[r^2, dr] from point1 (0,0) to point2 (1,1), which would be evaluated from r=0 to r=sqrt[2] and gives answer = 2*sqrt[2]/3. The above is pretty simple, however, I am not sure how to formulate the problem when I convert the 'dr' back to cartesian coordinates as follows: Integrate [x^2+y^2, d????] and the limits??? WHat should 'dr' be in terms of dx? if my integrand is directly x^2+y^2. It cannot be a double integral, since the original problem was a single integral, but then how do you solve this?? Can anyone help? thanks!