Area Calculation for Circle and Cardioid Using Double Integrals

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SUMMARY

The discussion focuses on calculating the area inside the circle defined by the polar equation r=1 and outside the cardioid defined by r=1+cos(θ) using double integrals. Participants express confusion regarding the setup of the double integral, particularly in determining the correct limits for θ and r. The integration should be performed with r ranging from 1 to 1+cos(θ) and θ ranging from 0 to π, considering the symmetry of the regions involved. Visual aids, such as graphs, are recommended to clarify the intersection points and the areas of integration.

PREREQUISITES
  • Understanding of polar coordinates and their equations
  • Familiarity with double integrals in calculus
  • Knowledge of the cardioid and circle equations
  • Ability to interpret graphical representations of mathematical functions
NEXT STEPS
  • Study the setup of double integrals in polar coordinates
  • Learn how to determine intersection points of polar curves
  • Explore the concept of symmetry in integration
  • Practice visualizing regions of integration with graphing tools
USEFUL FOR

Students studying calculus, particularly those focused on polar coordinates and double integrals, as well as educators looking for examples of area calculations involving complex shapes.

stolencookie

Homework Statement


r=1 and r=1+cos(theta), use a double integral to find the area inside the circle r=1 and outside the cardioid r=1+cos(theta)

Homework Equations

The Attempt at a Solution


I am confused on the wording and how to set it up. I tried setting it up by setting theta 0 to pi. and r as 1 to 1+cos(theta). I used r drd(theta) as the equation to use.
 
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stolencookie said:

Homework Statement


r=1 and r=1+cos(theta), use a double integral to find the area inside the circle r=1 and outside the cardioid r=1+cos(theta)
...

I am confused on the wording and how to set it up.
Make a picture !
upload_2017-12-1_18-21-19.png
 

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BvU said:
Make a picture !
View attachment 215925
I did make a picture I am confused by the little piece of the cardoid that isn't in the first quadrant.
 
stolencookie said:
I did make a picture I am confused by the little piece of the cardoid that isn't in the first quadrant.

In the whole plane, what is the region outside the cardioid? What is the region inside the circle? What is the intersection of those two regions?
 
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stolencookie said:
I tried setting it up by setting theta 0 to pi
As shown in BvU's graph, the region of integration is entirely on the left side of the vertical axis. What is ##\theta## at the upper intersection point? At the lower intersection point? There is also some symmetry you can take advantage of.
 
stolencookie said:
little piece of the cardoid that isn't in the first quadrant
Ambiguous -- in the picture a small piece is missing because I simply didn't grab the full ##\theta## range for the red curve :smile:
 

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