Applications of Integration: Arc Length

1 / 22

# Applications of Integration: Arc Length - PowerPoint PPT Presentation

Applications of Integration: Arc Length. Dr. Dillon Calculus II Fall 1999 SPSU. Start with something easy. The length of the line segment joining points (x 0 ,y 0 ) and (x 1 ,y 1 ) is. (x 1 ,y 1 ). (x 0 ,y 0 ). The Length of a Polygonal Path?. Add the lengths of the line segments.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'Applications of Integration: Arc Length' - brandee

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### Applications of Integration: Arc Length

Dr. Dillon

Calculus II

Fall 1999

SPSU

The length of the line segment joining points (x0,y0) and (x1,y1) is

(x1,y1)

(x0,y0)

The Length of a Polygonal Path?

Add the lengths of the line segments.

The length of a curve?

Approximate by chopping it into polygonal pieces and adding up the lengths of the pieces

What is the approximate length of your curve?
• Say there are n line segments
• our example has 18
• The ith segment connects (xi-1, yi-1) and (xi, yi)

(xi-1,yi-1)

(xi, yi)

The length of the polygonal path is thus...

which is the approximate length of the curve

What do we do to get the actual length of the curve?
• The idea is to get the length of the curve in terms of an equation which describes the curve.
• Note that our approximation improves when we take more polygonal pieces
A Basic Assumption...

We can always view y as a function of x, at least locally (just looking at one little piece of the curve)

And if you don’t buy that…

we can view x as a function of y when we can’t view y as a function of x...

To keep our discussion simple...

Assume that y is a function of x

and that y is differentiable

with a continuous derivative

Using the delta notation, we now have…

The length of the curve is approximately

Simplify the summands...

Factor out

And from there

What? Where’d you get that?

Recall that

Where the limit is taken over all partitions

And

In this setting...

Playing the role of F(xi) we have

And to make things more interesting

than usual,

What are a and b?

The x coordinates of the endpoints of the arc

Endpoints? Our arc crossed over itself!

One way to deal with that would be to treat the arc in sections.

Find the length of the each section, then add.

a

b

Conclusion?

If a curve is described by y=f(x) on the interval [a,b]

then the length L of the curve is given by