# Reparametrization to find arc length

1. Sep 21, 2011

### llooppii

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

Reparametrize the curve with respect to arc length measured from the point where t=0 in the direction of increasing t.

r(t) = [e^(2t)cos(2t)]i+2j+[e^(2t)sin(2t)]k

2. Relevant equations

i know that the derivative of the arc length with respect to t = magnitude of the derivative of r(t).

3. The attempt at a solution

I found the derivative and found the magnitude, but am basically lost as of there.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Sep 21, 2011

### lanedance

start by finding the arc length as function of t

3. Sep 22, 2011

### icystrike

Let s(t) be the arc length, and I'm sure Ur calculus textbook will have the formula of arc length..

4. Sep 22, 2011

### icystrike

In fact you can easily "derive" the formula with pythagorus theorem and riemman sum in mind.