# Homework Help: Find the volume

1. Dec 1, 2012

2. Dec 1, 2012

### Staff: Mentor

You have a mistake on the next-to-last line. You have evaluated your antiderivative in the wrong order. Inside the parentheses you should have ln(sin($\pi/2$)) - ln(sin($\pi/6$)).

Also, the differential -- dx or du -- should appear in every step until you actually get the antiderivative.

When you make your substitution, that's when you should either change your limits of integration or at least make a note that the limits are values of x, not u. Here's what I mean:

$$\pi \int_{x = \pi/6}^{\pi/2} \frac{du}{u}$$

By including "x = ..." in one of the limits of integration, that reminds you not to use them directly in the antiderivative that you get.

3. Dec 1, 2012

### manal950

which line I got mistake is last line or what ?

4. Dec 1, 2012

### Staff: Mentor

I said which line in my last post.

5. Dec 2, 2012

### SammyS

Staff Emeritus
I pointed out this same omission in your previous thread.

6. Dec 2, 2012

### manal950

Is the final answer is = 2.17 ?

7. Dec 2, 2012

### manal950

Is the final answer will be = 2.17 ?

anyone help ?

8. Dec 2, 2012

### Staff: Mentor

If you round to 2 decimal places, the answer is 2.18.

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