# Arc length integral

1. Mar 27, 2009

### hachi_roku

1. The problem statement, all variables and given/known data

ok, the original prob is : find the length of the curve of y=ln(1-x^2) x between 0, 1/2.

2. Relevant equations

3. The attempt at a solution
ive made it this far: my integral is -1 + 2/1-x^2..............ok so i decompose the second part but in doing so i get a negative to make it -(x+1)(x-1) but i don't know what happens to that negative because the solution manual says the integral is .......-1+ 1/x+1 -1/x-1 dx i don't get the signs. please help!

2. Mar 27, 2009

### sutupidmath

if we are woking with single variable functions, y=f(x) like here then the arc length from a to be of a curve is:

$$L=\int_a^b\sqrt{1+[f'(x)]^2}dx$$

3. Mar 27, 2009

### hachi_roku

yes....like i said ive already worked that part....im toward the end of the problem i just don't get the signs

4. Mar 27, 2009

### sutupidmath

Well, since you have shown almost no work(step by step) it is hard to tell where you have missed, or what you are doing wrong.

5. Mar 27, 2009

### hachi_roku

got it...nvm..thanks

6. Mar 27, 2009