Circular lawn

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

Result

S =  1660 m²

Solution:

$o = 2 \pi r \ \\ r = o/(2\pi) = 24.987 \ \\ S = \pi (r-2)^2 = \pi (24.987-2)^2 = 1660 \ \text{m}^2$

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