# Line integral

1. Oct 28, 2011

### wasi-uz-zaman

Hi experts
what is line integral - for example if I can draw graph of parabola and i can calculate the area under the graph. But how can i measure the length of parabolic path.

2. Oct 28, 2011

### mathman

Let s be arc length. Then the differential of arc length is given by:

ds=√(dx2+dy2)=√(1+(dy/dx)2)dx.

To get the arc length between 2 values of x, integrate ds between those values.

3. Oct 28, 2011

### paulfr

Two entirely different concepts
A line integral is more complex idea than the area under a curve in 2 dimensions.
It is done in 3 dimensions [or more]
The arc length is an application of integration in 2 D and the formula was given to yoou in the previous post.

4. Oct 28, 2011

### wasi-uz-zaman

thanks alot you have solved my query.