Annulus

Calculate the area of two circles annulus k1 (S, 3 cm) and k2 (S, 5 cm).

Correct result:

S =  50.27 m2

Solution:

r1=3 cm r2=5 cm S1=π r12=3.1416 3228.2743 cm2 S2=π r22=3.1416 5278.5398 cm2  S=S2S1=78.539828.2743=50.27 m2r_{1}=3 \ \text{cm} \ \\ r_{2}=5 \ \text{cm} \ \\ S_{1}=\pi \cdot \ r_{1}^2=3.1416 \cdot \ 3^2 \doteq 28.2743 \ \text{cm}^2 \ \\ S_{2}=\pi \cdot \ r_{2}^2=3.1416 \cdot \ 5^2 \doteq 78.5398 \ \text{cm}^2 \ \\ \ \\ S=S_{2} -S_{1}=78.5398 -28.2743=50.27 \ \text{m}^2



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