Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Volume of a solid

  1. Jun 29, 2003 #1

    Dx

    User Avatar

    3) Find the volume of the solid that lies below the surface z = f(x,y) and above region in xy plane: z = 3+cos(x) + cos(y); x = 0; x = PI; y = 0; y=PI.

    V=double integral_R f(x,y)dA; f(x,y)= 3 + cos(x) + cos(y); 0<= x <= PI and 0 <= PI so V = integral PI ro 0 (integral PI to 0 (3 + cos(x) + cos(y))dy)dx = ???

    I am using a example in my book but am stuck here or confused if I am going in the right direction. plz help?
    Thanks!
    Dx :wink:
     
  2. jcsd
  3. Jun 30, 2003 #2

    HallsofIvy

    User Avatar
    Science Advisor

    The only comment I would make is that it would make more sense to integrate from 0 to pi than from pi to 0!

    Of course, since cos(x) and cos(y) are never less than -1,
    3+ cos(x)+ cos(y) is never 0 so the function surface is always above the x,y plane.

    Now, go ahead and do the integral. (I get 3pi2.)
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook