# I'm supposed to find the length of the curve.

1. Feb 22, 2009

### afcwestwarrior

I got up to here. L = ∫ √(1 + sec^4 (t)) dt

oh yea it's from 0,<= t <= pi/4

do I have to pull a sec^2 t out or do I just square it, I don't think I can use the square root yet unless is was just sec^4 t by itself.

I need help man.

2. Feb 22, 2009

### gabbagabbahey

This integral cannot be expressed in terms of elementary functions

Are you sure that your steps leading up to this point are correct? What was the original problem?

3. Feb 22, 2009

### afcwestwarrior

The original problem was r(t)= < sin t, cos t, tan t> 0 <= t <=pi/4

It asked me too find the length of the curve to four decimal places. It told me to use my calculator to approximate the integral.

4. Feb 22, 2009

### afcwestwarrior

They also came up with an answer. L = 1.2780

5. Feb 22, 2009

### gabbagabbahey

Okay, then you've come up with the correct integral. However, it is much easier to evaluate numerically than to try it analytically.

What numerical approximation methods have you been taught? Apply one of them.

6. Feb 22, 2009

### afcwestwarrior

So I just plug in the values o and pi/4

7. Feb 22, 2009

### afcwestwarrior

I don't think I've been taught any numerical approximation methods yet. We barely went through this section.

8. Feb 22, 2009

### afcwestwarrior

Wait a minute. Wouldn't I use series or something.

9. Feb 22, 2009

### afcwestwarrior

What method would you use.

10. Feb 23, 2009

### gabbagabbahey

I would probably use either the Trapezoid rule, or Simpson's rule....have you been taught either of those?