Answer:
40π m² and 125.6 m²
Step-by-step explanation:
the area (A) of the sidewalk is calculated as
A = outer area - inner area
(a)
A = πr₁² - πr₂² ( r₁ is radius of outer circle and r₂ the radius of inner circle )
A = π × 11² - π × 9²
= 121π - 81π
= 40π m²
(b)
A = 40 × 3.14 = 125.6 m²
