The collar

The collar on the dress has the shape of an annulus 6 cm wide. The circumference of the inner circle is 31.4 cm. How much cm2 of fabric is needed to make one collar?

Correct answer:

S =  301.4973 cm2

Step-by-step explanation:

h=6 cm o2=31.4 cm  r2=o2/(2π)=31.4/(2 3.1416)4.9975 cm r1=r2+h=4.9975+610.9975 cm  S1=π r12=3.1416 10.99752379.9575 cm2 S2=π r22=3.1416 4.9975278.4602 cm2  S=S1S2=379.957578.4602=301.4973 cm2



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