- #1
velouria131
- 13
- 0
Alright. I completely confused about determining the area between regions of polar curves. However, I do feel that I have a solid grasp in finding areas for single functions. For a given function in polar form, I know that I find the limits of integration by setting the function equal to zero and solving for those theta values. This is the area "swept out". When presented with two functions, I understand that I must set them equal to find points of intersection. I do not know how to apply these points of intersection. For two given curves, do I take the difference of the integrals from those two shared points?
Here is an example:
The region inside the rose r = 4sin2θ and r = 2.
Equation = 1/2 ∫α→β (f(θ)^2 - g(θ)^2)dθ
I set these two functions equal.
sin2θ = 1/2
2θ = pi/6 , 5pi/6...
θ = pi/12 , 5pi/12...
When I look at the graph of this function, I see that I want the areas inside the circle r = 2 that belong to the other function. I should calculate the area of one section and multiply it by 4 to find the total area. I do not see how I can compute the partial area for this by using those two points of intersection. There seems to be one point I am missing or something and I cannot seem to figure out how to find it. Am I missing a theta value for which sin = 1/2 ?Even if I had two points, I do not understand how the I would take difference of those two areas to find this. If I took the difference in area of r = 4sin2θ and r = 2 , I would have the area outside of the circle. If I did the opposite, I would have negative area.
Thanks for reading this and helping.
Here is an example:
The region inside the rose r = 4sin2θ and r = 2.
Equation = 1/2 ∫α→β (f(θ)^2 - g(θ)^2)dθ
I set these two functions equal.
sin2θ = 1/2
2θ = pi/6 , 5pi/6...
θ = pi/12 , 5pi/12...
When I look at the graph of this function, I see that I want the areas inside the circle r = 2 that belong to the other function. I should calculate the area of one section and multiply it by 4 to find the total area. I do not see how I can compute the partial area for this by using those two points of intersection. There seems to be one point I am missing or something and I cannot seem to figure out how to find it. Am I missing a theta value for which sin = 1/2 ?Even if I had two points, I do not understand how the I would take difference of those two areas to find this. If I took the difference in area of r = 4sin2θ and r = 2 , I would have the area outside of the circle. If I did the opposite, I would have negative area.
Thanks for reading this and helping.