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Jason designed an arch made of wrought iron for the top of a mall entrance. The 11 segments between the two concentric circles are each 1.25 m long. Find the total length of wrought iron used to make the structure. Round the answer to the nearest meter.

 Jun 24, 2014

Best Answer 

 #3
avatar+118608 
+10

Do you mean that the radius of the big one is 7.5m across and the radius of the little one is 5m accross

$$\begin{array}{rll}
Area &=& 0.5[\pi\times 7.5^2 - \pi\times 5^2]\\\\
&=& 0.5\pi[56.25-25]\\\\
&=& 0.5\pi\times 31.25\\\\
&=& 0.5\pi\times 31.25\\\\
&=& 49.087\\\\
&=& 49\:m^2
\end{array}$$

 Jun 25, 2014
 #1
avatar+118608 
+5

Natasza, do you mean that the arch is a half the area between 2 concentric cicles where the difference in the 2 radii is 1.25m?  the question is quite confusing.  What has the 11 sebments got to do with anything?

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 Jun 25, 2014
 #2
avatar+279 
0

Yes, Melody! Sorry for no picture. The document I Got this From Is on Microsoft Word :(

At the floor of The Arch, It Is 15 Meters.

:)

 Jun 25, 2014
 #3
avatar+118608 
+10
Best Answer

Do you mean that the radius of the big one is 7.5m across and the radius of the little one is 5m accross

$$\begin{array}{rll}
Area &=& 0.5[\pi\times 7.5^2 - \pi\times 5^2]\\\\
&=& 0.5\pi[56.25-25]\\\\
&=& 0.5\pi\times 31.25\\\\
&=& 0.5\pi\times 31.25\\\\
&=& 49.087\\\\
&=& 49\:m^2
\end{array}$$

Melody Jun 25, 2014

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