Growth of city area

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mary818

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Mar 16, 2006
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word problem

The boundary of a city is a circle of diameter 10 miles. Within the last decade, the city has grown in area by approximately 50mi^2. Assuming the city was always circular in shape, find the corresponding change in distance from the center of the city to the boundary.

I'm completely at a loss. Do I need the formula for the area of a circular? If i do, do I plug in #'s and if so what?
 
Please post new questions as new threads, not as "hijacks" of unrelated threads.

Thank you.

Eliz.
 
I have moved this topic to its own thread in the Geometry section. That's why Stapel's post seems kind of odd ;)
 
Yes, the Area is now
A = pi*r² = pi*5².
It was A-50=pi(5-x)²
Solve for x.
 
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