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Topic: geometry
Replies: 1   Last Post: Apr 29, 2004 1:14 AM

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Vladimir Zajic

Posts: 319
Registered: 12/3/04
Re: geometry
Posted: Apr 29, 2004 1:14 AM
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On 14 Apr 04 00:02:17 -0400 (EDT), michael wrote:
>construct a circular target with nine regions of equalarea, with one
>circle in the middle and spokes going out to the edge. if the whole
>circle is 6 feet in diameter, what will the diameter of the inner
>circle be?

R = 3 ft is the target radius
r is the radius of the inner circle

Area of the inner circle:
A(C) = ¶r²

Area of each spoke region (8 of them):
A(S) = (¶R² - ¶r²)/8

The area of each spoke region is equal to the area of the inner
A(S) = A(C)

(¶R² - ¶r²)/8 = ¶r²
R² = 9r²
R = 3r
r = R/3 = 3/3 = 1 ft

Diameter of the inner circle:
d = 2r = 2 ft

Date Subject Author
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Vladimir Zajic

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