Question about finding area using Green's Theorem

In summary, the conversation discusses using Green's Theorem to find the area of a region between the x-axis and a parameterized curve. The speaker has been able to identify the boundaries for the double integral, but is unsure how to proceed without the vector field equation. The other person suggests using an integral of the form $$ \int \int_D 1 \, dA $$ and asks the speaker about the values of P and Q in that case. The speaker is unsure and asks for confirmation. The other person suggests the speaker calculate the values based on the given information.
  • #1
Mohamed Abdul

Homework Statement


Use Green's Theorem to find the area of the region between the x-axis and the curve parameterized by r(t)=<t-sin(t), 1-cos(t)>, 0 <= t <= 2pi

Attached is a figure pertaining to the question

Bqenm90.png


Homework Equations



eq0001M.gif
[/B]

The Attempt at a Solution



Using the parameterized curve, I have been able to locate the x boundaries between 0 and 2pi and the y boundaries between 0 and 1-cos(t). However, I do not know how to proceed with the double integral because I don't have the vector field equation. Can anyone help me out?
 

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  • #2
Mohamed Abdul said:

Homework Statement


Use Green's Theorem to find the area of the region between the x-axis and the curve parameterized by r(t)=<t-sin(t), 1-cos(t)>, 0 <= t <= 2pi

Attached is a figure pertaining to the question

View attachment 214363

Homework Equations



View attachment 214364 [/B]

The Attempt at a Solution



Using the parameterized curve, I have been able to locate the x boundaries between 0 and 2pi and the y boundaries between 0 and 1-cos(t). However, I do not know how to proceed with the double integral because I don't have the vector field equation. Can anyone help me out?

You want to end up with an integral of the form
$$ \int \int_D 1 \, dA, $$
so what does that tell you about ##P## and ##Q##?
 
  • Like
Likes Charles Link
  • #3
Ray Vickson said:
You want to end up with an integral of the form
$$ \int \int_D 1 \, dA, $$
so what does that tell you about ##P## and ##Q##?
Would P and Q just be 1 in that case?
 
  • #4
Mohamed Abdul said:
Would P and Q just be 1 in that case?
You tell me. Do you get the right value of ##\partial Q/ \partial x - \partial P / \partial y##?
 

1. What is Green's Theorem and how is it used to find area?

Green's Theorem is a mathematical theorem that relates the line integral of a curve to the double integral of the region bounded by the curve. It is used to find the area of a closed curve in a two-dimensional plane by converting the line integral into a double integral, making it easier to calculate.

2. What is the formula for Green's Theorem?

The formula for Green's Theorem is: ∫C P dx + Q dy = ∬D (∂Q/∂x - ∂P/∂y) dA, where C is the closed curve, P and Q are functions of x and y, and D is the region bounded by the curve.

3. How does Green's Theorem relate to the divergence theorem?

Green's Theorem is a special case of the divergence theorem, which relates the line integral of a vector field over a closed curve to the triple integral of the divergence of the field over the region bounded by the curve. Green's Theorem only applies to two-dimensional vector fields, while the divergence theorem applies to three-dimensional vector fields.

4. Can Green's Theorem be used for any type of curve?

No, Green's Theorem can only be used for closed curves, meaning that the starting and ending points of the curve must be the same. Additionally, the curve must be smooth and continuously differentiable.

5. Are there any limitations to using Green's Theorem to find area?

Yes, Green's Theorem can only be used to find the area of a closed curve in a two-dimensional plane. It cannot be used for curves in higher dimensions or for finding the volume of a solid bounded by a surface in three-dimensional space.

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