A community for students.
Here's the question you clicked on:
 0 viewing
 2 years ago
Area between two polar curves?
Find the area inside the circle r = 3*a*cosx and outside the cardiod r = a*cosx + a, where a > 0
 2 years ago
Area between two polar curves? Find the area inside the circle r = 3*a*cosx and outside the cardiod r = a*cosx + a, where a > 0

This Question is Closed

JamesJ
 2 years ago
Best ResponseYou've already chosen the best response.0So always start with a diagram: I'll let you draw that. It's not too bad. Call the first function r1. That is r1 = 3a.cos(theta) , and I assume by the way you meant to write theta, not x? And the second function r2. Then the area is the integral \[ \int_0^{2\pi} \int_{r_2}^{r_1} r \ dr \ d\theta \]

David.Butler
 2 years ago
Best ResponseYou've already chosen the best response.0Why are the bounds for the second integral 0 to 2pi ? They intersect at pi/3 and 5pi/3. Thanks , I truly appreciate the help.

JamesJ
 2 years ago
Best ResponseYou've already chosen the best response.0Ah, good. In which case, that's the range of values for theta.

JamesJ
 2 years ago
Best ResponseYou've already chosen the best response.0Another good reason to draw the graph!

zepdrix
 2 years ago
Best ResponseYou've already chosen the best response.2dw:1359669259799:dwHmm I was trying to draw the graph :L it's pretty tricky though lol

zepdrix
 2 years ago
Best ResponseYou've already chosen the best response.2The circle is drawn by the `outer` radius, so we subtract the inner radius from the outer.\[\large \int\limits_{\pi/3}^{\pi/3} 3a \cos x(a \cos x+a) \quad dx\] Is the lower limit 5pi/3? I think it's pi/3. a>0.. Hmm maybe not. Grr now I'm confusing myself :) lol

David.Butler
 2 years ago
Best ResponseYou've already chosen the best response.0Oh no your right! Thanks , I kept doing the problem wrong , I was using the wrong bounds! Thanks So much
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.