Around

Around the circular flowerbed with a radius of 2 m is a sidewalk 80 cm wide. How many square meters does the sidewalk have?

Correct answer:

S =  12.0637 m²

Step-by-step explanation:

$$\begin{gathered} r_1=2\text{ m } \\ x=80\text{ cm}\to \text{ m}=80\mathrm{/}100\text{ m}=0.8\text{ m } \\ {r}_2=r_1+x=2+0.8={\displaystyle \frac{14}{5}}=2.8\text{ m } \\ {S}_1=\pi \cdot r_1^2=3.1416\cdot 2^2\doteq 12.5664{\text{m}}^2 \\ {S}_2=\pi \cdot r_2^2=3.1416\cdot 2.8^2\doteq 24.6301{\text{m}}^2 \\ S=S_2-S_1=24.6301-12.5664=12.0637{\text{m}}^2 \end{gathered}$$

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