Circular lawn

Around a circular lawn area is a 2 m wide sidewalk. The outer edge of the sidewalk is a curb whose width is 2 m. The Curbstone and the inner side of the sidewalk together form concentric circles. Calculate the area of the circular lawn, and the result round to 10's m².

Final Answer:

S =  1660.1 m²

Step-by-step explanation:

$$\begin{gathered} a=2\text{m} \\ o=157\text{m} \\ o=2\pi r \\ r=o/(2\pi )=157/(2\cdot 3.1416)\doteq 24.9873\text{m} \\ {r}_2=r-a=24.9873-2\doteq 22.9873\text{m} \\ S=\pi \cdot r_2^2=3.1416\cdot 22.9873^2=1660.1{\text{m}}^2 \end{gathered}$$

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