Finding the Correct Parameterization for Line Integral

In summary, the question is about finding a line integral for a triangle with given vertices using a specific equation, and the poster is having trouble with parameterization.
  • #1
Darkmisc
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27

Homework Statement



I'm attempting Q 3 from ch 16.4 of Stewart (p 1060).

We are required to find the line integral where C is the triangle with vertices (0,0), (1,0) and (1,2).

The line integral is

Int xy dx + x^2*y^3 dy




Homework Equations





The Attempt at a Solution



I'm having trouble parametizing the vertical line between (1,0) and (1,2).

I'd let y = 2t and x = 1, but got the wrong final answer. I suspect it's because line (1,0) to (1,2) was incorrectly expressed.

I then wanted to integrate in terms of dy, with terminals for y of 0 and 2, and parametizing y in terms of y, but where does that leave the dx in the first part of the equation?

I imagine it would be easier to use Green's Theorem, but the question specifically requires the use of line integrals.
 
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  • #2
Darkmisc said:

Homework Statement



I'm attempting Q 3 from ch 16.4 of Stewart (p 1060).

We are required to find the line integral where C is the triangle with vertices (0,0), (1,0) and (1,2).

The line integral is

Int xy dx + x^2*y^3 dy

Homework Equations


The Attempt at a Solution



I'm having trouble parametizing the vertical line between (1,0) and (1,2).

I'd let y = 2t and x = 1, but got the wrong final answer. I suspect it's because line (1,0) to (1,2) was incorrectly expressed.

I then wanted to integrate in terms of dy, with terminals for y of 0 and 2, and parametizing y in terms of y, but where does that leave the dx in the first part of the equation?

I imagine it would be easier to use Green's Theorem, but the question specifically requires the use of line integrals.
Both parameterizations would work, but you haven't provided enough detail for us to see where you went wrong. In either case, x is a constant, so the dx term drops out.
 

1. What is a line integral over a triangle?

A line integral over a triangle is a type of mathematical calculation that involves integrating a function along a specific path over a triangular region. It is often used in physics and engineering to calculate quantities such as work, flux, and circulation.

2. How is a line integral over a triangle different from a regular line integral?

A line integral over a triangle differs from a regular line integral in that it involves integrating over a triangular region rather than a straight line. This means that the path of integration is not a single line, but rather a connected series of line segments forming a triangle.

3. What are the applications of a line integral over a triangle?

A line integral over a triangle has various applications in physics and engineering. It can be used to calculate work done by a force over a triangular region, the flux of a vector field through a triangle, and the circulation of a vector field along the boundary of a triangle.

4. How is a line integral over a triangle calculated?

To calculate a line integral over a triangle, the path of integration is divided into smaller line segments and the function is evaluated at each point along the path. The sums of these values are then multiplied by the length of each line segment and added together to get the total integral.

5. Are there any special properties of a line integral over a triangle?

Yes, there are several special properties of a line integral over a triangle. For example, the value of the integral is independent of the path chosen within the triangle, as long as the endpoints remain the same. Additionally, the integral can be broken down into smaller integrals over each side of the triangle, making it easier to calculate.

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