# Science talk:Math Exam Resources/Courses/MATH101/April 2009/Question 3 (b)

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Thread title | Replies | Last modified |
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April 2009 - 3b | 1 | 00:04, 11 April 2012 |

3b apr 2009 answer | 1 | 21:48, 8 April 2012 |

Math 101 2009 April exam 3b | 1 | 02:06, 7 April 2012 |

The answer displayed is pi integral ((arccos(y))^2 + 2arccos(y)) dy. Shouldn't it be pi integral ((arccos(y))^2 + *4*arccos(y)) dy?

I thought:

(arccos(y) + 2)^2 - 2^2

= (arccos(y))^2 + 4arccos(y) + 4 - 4

EDIT: this would lead to the pi^2 + 2pi answer that Amy got.

Brian

For the answer of this question, I was practicing my integration and instead of the answer pi squared, I got pi squared + 2pi. I was wondering whether is correct or not.

Amy

Hello Amy. Wolframalpha says it's π^{2}. If you want to post your steps we can see where you went wrong. Your answer is not far off, so probably you just overlooked a minor thing?