Parametric Equation intersection and area

In summary, the problem is to find the area of the region outside the first curve, r=2sin(θ), and inside the second curve, r=2sin(2θ), for 0≤θ≤π/2. The solution involves setting up an intersection to find the bounds for the integrals, but the initial limits provided are incorrect.
  • #1
BradyK
1
0

Homework Statement


Given the curves r=2sin(θ) and r=2sin(2θ), 0 ≤ θ ≤ pi/2, find the area of the region outside the first curve and inside the second curve


Homework Equations


obviously set up an intersection to see where the two meet, then subtract the circle equation from the rose equation.


The Attempt at a Solution



First setting up the intersection:
2sin(θ) = 2sin(2θ)
sin(θ) = sin(2θ)
sin(θ) = 2sin(θ)cos(θ)
1 = 2cos(θ)
1/2 = cos(θ)
pi/3 = θ

so then setting up the integrals, you have sin(θ) dθ bound by pi/3 to pi/2 minus 2sin(2θ) dθ bound by pi/3 to pi/2

working through it, I was able to get an answer of 1/2, but entering it in, the answer turned out to be incorrect. Any help here would be greatly appreciated, thank you.
 
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  • #2
BradyK said:
so then setting up the integrals, you have sin(θ) dθ bound by pi/3 to pi/2 minus 2sin(2θ) dθ bound by pi/3 to pi/2

working through it, I was able to get an answer of 1/2, but entering it in, the answer turned out to be incorrect. Any help here would be greatly appreciated, thank you.

Hi BradyK! Welcome to PF! :smile:

You should recheck those limits. You are looking for the area outside the first curve r=2sin(θ) and inside the second curve r=2sin(2θ).
 

Related to Parametric Equation intersection and area

1. What is a parametric equation?

A parametric equation is a mathematical representation of a curve or surface in which the coordinates of each point are expressed as functions of one or more independent variables, called parameters. This allows for a more flexible and precise description of curves and surfaces compared to traditional equations.

2. How do you find the intersection of two parametric equations?

To find the intersection of two parametric equations, set the two equations equal to each other and solve for the common variables. This will give the coordinates of the point(s) of intersection. If the equations do not have a common variable, they do not intersect.

3. Can parametric equations be used to find the area between curves?

Yes, parametric equations can be used to find the area between curves. This is done by finding the points of intersection between the two curves, and then using the parametric equations to find the corresponding x and y values at each point. The area can then be calculated using the formula for the area under a curve.

4. What is the advantage of using parametric equations to describe curves?

Parametric equations allow for a more flexible and precise description of curves compared to traditional equations. They also make it easier to describe complex curves, such as spirals or ellipses, which can be difficult to express using traditional equations.

5. How can parametric equations be used in real-world applications?

Parametric equations have many practical applications in fields such as physics, engineering, and computer graphics. They can be used to describe the motion of objects, model natural phenomena, and create 3D animations and special effects. They are also commonly used in parametric design, which involves using mathematical equations to generate shapes and patterns.

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