1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Surface area problem in 3-d calculus

  1. Apr 15, 2008 #1
    1. The problem statement, all variables and given/known data

    Find the area of the surface.
    The surface z = (2/3)(x^(3/2) + y^(3/2)), 0 </= x </= 1, 0 </= y </= 1

    2. Relevant equations

    Double integral over S of the magnitude of dr/du cross dr/dv dS, which equals the double integral over D of the magnitude of dr/du cross dr/dv dA.
    (SSs |dz/dx X dz/dy|dS = SS D |dz/dx X dz/dy|dA)

    3. The attempt at a solution
    _ 1 1
    I found the integral to be SS D (1+x+y)^(1/2) dA = SS (1+x+y)^(1/2) dxdy
    _ 0 0
    but my answer keeps coming out wrong. I might be making a mistake with algebra because I get a lot of different answers when i do it different ways. This is from an NC State Calculus 3 homework assignment, if anyone may have seen this problem before and remember how to do it. Help???
    Last edited: Apr 15, 2008
  2. jcsd
  3. Apr 15, 2008 #2


    User Avatar
    Science Advisor

    What you have shown is completely correct. Now, how did you do that integration and what answer did you get?
  4. Apr 15, 2008 #3
    I got the right answer finally, 1.4066. It was an algebraic error when I was evaluating the integral. Thanks for telling me I was doing it right though, that helped me know it wasn't a mistake in my set-up.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook