• Support PF! Buy your school textbooks, materials and every day products Here!

Double integrate help

  • Thread starter iamwilson
  • Start date
12
0
1. Homework Statement

Using polar coordinates, evaluate the integral which gives the area which lies in the first quadrant below the line y=7,and between the circles x^2 + y^2 = 196 and x^2 - 14x + y^2 = 0.

2. Homework Equations



3. The Attempt at a Solution

i tried to double integrate from 0<theta<pi/2, 7-14cos(theta)<r<7 with rdrd(theta) but that was not the correct answe, can someone tell me with i did wrong with the r values
 

Answers and Replies

Dick
Science Advisor
Homework Helper
26,258
618
Did you draw a picture of the region you are integrating? If I'm drawing it correctly it doesn't look like you can do it as a single integral. You'll need to break it into pieces and think about using different origins for the polar coordinates for different pieces. Looks kind of nasty.
 
12
0
yes, i did, even ask my professor on how to doing it, but she only gave me the r=7+7cos(theta) but that doesn't make sense, i thought it's 14cos(theta), Dick, i completely loss, can anyone help me on this one
 
Dick
Science Advisor
Homework Helper
26,258
618
First of all there are three curves to worry about. The circle of radius 14, the circle of radius 7 and the line y=7. Which one corresponds to the polar equation r=7+7cos(theta)? What are the polar equations of the other two?
 

Related Threads for: Double integrate help

  • Last Post
Replies
4
Views
746
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
1
Views
5K
  • Last Post
Replies
6
Views
684
  • Last Post
Replies
2
Views
863
  • Last Post
Replies
2
Views
738
  • Last Post
Replies
5
Views
1K
Top