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posted by  maret on 11/24/2008 12:37:34 PM  |  status: Closed  

Definite Integral..Will Rate-please help!

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Calculus N/A N/A N/A
Question Details:
Use a geometric formula to evaluate the definite itegral
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posted by Bart_Boy on 11/24/2008 12:40:59 PM  |  status: Live
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maret's comment:
"Thanks!"
Response Details:
This is one quarter of a circle of radius 3. 



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posted by peterjacks on 11/24/2008 12:56:28 PM  |  status: Live
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Response Details:
√(9-x^2) = y
 
9-x^2 = y^2
 
9 = y^2 + x^2
 
*note* This is the equation for a circle with radius 3 (But also note the squareroot makes it only the top half of the circle)
 
So, integrating it from 0 to 3 will give you the one-forth the area of the circle
 
area=πr^2
 
area = π(3)^2 = 9π
 
Divide this by 4, becuase we are only looking for a part of the circle.
 
So, the answer is
= (9π)/4
-Peter Jackson
Tags: Calculus
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