Finding Boundaries of a Definition Area

In summary, the OP has trouble integrating a double integral that has boundary conditions between two circles with radii of 1 and 3. The first boundary is obviously pi/4 and/or 3pi/4, and the answer is pi/3. However, the OP has difficulty finding a way to get this result and has not provided a picture or explanation.
  • #1
Wi_N
119
8

Homework Statement


Problem is part of a double integral. but my boundries are:

1<=x^2 + y^2 <=9 so between 2 circles with r1=1 and r2=3

and x<=y and y<=sqrt(3x)

the first boundry is obviously pi/4 and/or 3pi/4

the answer is pi/3 and i have no idea how u get that.

u obviously have to switch to polar coordinates but x=rcost y=rsint have no resulted in anything.
 
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  • #2
Wi_N said:

Homework Statement


Problem is part of a double integral. but my boundries are:

1<=x^2 + y^2 <=9 so between 2 circles with r1=1 and r2=3

and x<=y and y<=sqrt(3x)

the first boundry is obviously pi/4 and/or 3pi/4
If you mean ##\theta = \frac \pi 4##, then yes, that is a boundary, but ##\theta = \frac {3\pi} 4## isn't a boundary.
Wi_N said:
the answer is pi/3 and i have no idea how u get that.
Nor do we, since you haven't told us what you're integrating or shown how you got your result.
Wi_N said:
u obviously have to switch to polar coordinates but x=rcost y=rsint have no resulted in anything.
Are you assuming that the line boundary and the quadratic boundary intersect on the outer circle?
 
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  • #3
Wi_N said:

Homework Statement


Problem is part of a double integral. but my boundries are:

1<=x^2 + y^2 <=9 so between 2 circles with r1=1 and r2=3

and x<=y and y<=sqrt(3x)

the first boundry is obviously pi/4 and/or 3pi/4

the answer is pi/3 and i have no idea how u get that.
Have you drawn a picture including ##y =\sqrt 3 x##? What is its slope? Angle of inclination? That will tell you how to get ##\theta## for it.
 
  • #4
Wi_N said:
y<=sqrt(3x)

LCKurtz said:
Have you drawn a picture including ##y =\sqrt 3 x##?
Per the OP, it is ##y \le \sqrt{3x}##, not ##y \le \sqrt 3x##.
 
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  • #5
Mark44 said:
Per the OP, it is ##y \le \sqrt{3x}##, not ##y \le \sqrt 3x##.
I'm guessing that the OP mistyped the problem, especially in light of what he says the answer is supposed to be.
 
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  • #6
LCKurtz said:
I'm guessing that the OP mistyped the problem, especially in light of what he says the answer is supposed to be.
Certainly within the realm of possibility.
 
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  • #7
you guys are right. thnks.
 

1. What is the definition of a boundary in a scientific context?

In science, a boundary is a line or area that separates two distinct regions or conditions. It can refer to physical boundaries, such as the edge of a cell or the border between two ecosystems, or conceptual boundaries, such as the limits of a scientific theory or the boundary between two scientific disciplines.

2. How do scientists determine the boundaries of a definition area?

Determining the boundaries of a definition area involves careful observation, data collection, and analysis. Scientists may use various tools and techniques, such as field surveys, experiments, and mathematical models, to gather information and identify patterns or thresholds that define the boundaries.

3. Why is it important to find boundaries of a definition area?

Finding boundaries of a definition area is crucial for understanding and accurately describing natural phenomena. It allows scientists to define and study specific systems or processes, make predictions, and identify potential impacts or changes. It also helps to establish common terminology and facilitate communication among scientists.

4. Can boundaries of a definition area change over time?

Yes, boundaries of a definition area can change over time. Natural systems are dynamic and constantly evolving, and external factors such as climate change, human activities, and natural disasters can alter the boundaries of a definition area. It is important for scientists to continuously monitor and reassess these boundaries to keep their understanding up-to-date.

5. How do scientists ensure the accuracy and reliability of their findings on boundaries of a definition area?

Scientists use a rigorous and systematic approach to ensure the accuracy and reliability of their findings on boundaries of a definition area. This includes using multiple methods and replicating experiments, peer-reviewing their work, and constantly testing and refining their theories and models. Collaboration and open communication with other scientists also help to validate and improve their findings.

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