September 12th, 2017, 05:37 PM  #1 
Member Joined: Feb 2017 From: East U.S. Posts: 40 Thanks: 0  Disk or Washer method
Hi guys, I'm having a little trouble setting this problem up: "Let R be the region bounded by the following curves. Use the disk or washer method to find the volume of the solid generated when R is revolved about the yaxis. y = x, y = 5x, y = 20" I can solve for the volume once I have the integral set up, but I'm a little confused on how to get the boundaries, as well as which function is being subtracted from the other. Normally I'll get two "y = ..." and two "x = ...", but I have three "y = ..." this time. Any tips would be great! Thank you. Last edited by nbg273; September 12th, 2017 at 05:39 PM. 
September 12th, 2017, 05:55 PM  #2 
Math Team Joined: Jul 2011 From: Texas Posts: 2,656 Thanks: 1327 
washers w/respect to y ... $\displaystyle A = \pi \int_0^{20} y^2  \left(\dfrac{y}{5}\right)^2 \, dy$ 

Tags 
disk, method, washer 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Washer Method  mr. jenkins  Calculus  6  May 14th, 2014 08:33 PM 
When do I use the washer method?  mortified_penguin  Calculus  13  December 28th, 2012 08:02 PM 
Disk/Washer Integration with ln function  brsystem  Calculus  4  September 16th, 2012 09:20 PM 
Difference between Disk/Washer and Cylindrical Shells  Obsessed_Math  Calculus  4  July 6th, 2012 10:36 PM 
Using the washer/shell/disk when solving in terms of y.  inspiration100  Calculus  1  March 8th, 2009 01:11 PM 