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Circumference of a circle is 40 π cm. A quarter of the circle represents the developer layer genuine coupe. Calculate the surface compartment.



Answer :

D3xt3R
we have to find the radius, how can we got it??

[tex]C=2\pi*r[/tex]

then

[tex]40\pi=2\pi*r[/tex]

[tex]\boxed{r=20~cm}[/tex]

A quarter of the circle will have a surface of a quarter of the circle, there fore

this is the surface of the circle

[tex]S=\pi*r^2[/tex]

a quarter of it

[tex]S_{\frac{1}{4}}=\frac{1}{4}*\pi*r^2[/tex]

then we can replace the value of r

[tex]S_{\frac{1}{4}}=\frac{1}{4}*\pi*20^2[/tex]

[tex]S_{\frac{1}{4}}=\frac{1}{4}*\pi*400[/tex]

we can simplify 

[tex]\boxed{\boxed{S_{\frac{1}{4}}=100\pi~cm^2}}[/tex]
kate200468
[tex]2 \pi r=40 \pi \ cm\ \ \ \Rightarrow\ \ \ r= \frac{40 \pi }{2 \pi } =20\\\\S= \pi r^2\ \ \ \Rightarrow\ \ \ quarter:\ \ A= \frac{1}{4} \cdot S= \frac{1}{4} \cdot \pi \cdot20\cdot20=100 \pi \ [cm^2] [/tex]

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