# Homework Help: Arc Length

1. Sep 20, 2010

### Larrytsai

1. The problem statement, all variables and given/known data
Find the arclength of the curve r(t)=(10t^2,2*sqrt(10)*t, ln t)
for 1<=t<=8

2. Relevant equations

3. The attempt at a solution
i took the derivative of each component of vector r

20t,2sqrt(10),1/t
then i square each term and square root it

int sqrt( 400t + 40 + 1/t^2)dt

i cant integrate this to find out the length tho.

2. Sep 21, 2010

### Staff: Mentor

400t should be 400t2.
If you make the change above, you'll have a perfect square that you can take the square root of.