1. The problem statement, all variables and given/known data Evaluate ∫∫S √(1 + x^2 + y^2) dS where S is the helicoid: r(u, v) = ucos(v)i + usin(v)j + vk, with 0 ≤ u ≤ 4, 0 ≤ v ≤ 3π 3. The attempt at a solution What I tried to do was say x=ucos(v) and y=usin(v), then I plugged those into the sqrt(1+x^2+y^2) eq, which I ended up simplifying to sqrt(1+u) somehow. I then took the cross product of the surface eq differentiated (respect to u) with eq (respect to v). I found the length of that, which I somehow got to be sqrt(2). I then said that the intergal was ∫∫sqrt(1+u)*sqrt(2)du*dv where the limits of integration are the limits of u and v given above. Well this is wrong. Hah! Any help would be appreciated.