Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

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

 Messages: [ Previous | Next ] Topics: [ Previous | Next ]
 Vladimir Zajic Posts: 319 Registered: 12/3/04
Re: geometry
Posted: Apr 29, 2004 1:14 AM

On 14 Apr 04 00:02:17 -0400 (EDT), michael wrote:
>construct a circular target with nine regions of equalarea, with one
a
>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) = ÃÂ¶rÃÂ²

Area of each spoke region (8 of them):
A(S) = (ÃÂ¶RÃÂ² - ÃÂ¶rÃÂ²)/8

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

(ÃÂ¶RÃÂ² - ÃÂ¶rÃÂ²)/8 = ÃÂ¶rÃÂ²
RÃÂ² = 9rÃÂ²
R = 3r
r = R/3 = 3/3 = 1 ft

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

Date Subject Author
4/14/04 michael