Question

A circular park is surroundeed by a rod 21 m wide. If the radius of the park is 105 m, find the area of the road .

Answer 1

Radius of the park, r = 105 m
Radius of the park with the road, R = 105 + 21 = 126 m
Area of the road = Area of the park with the road − Area of the park
$$\begin{gathered} =\mathrm{\pi }{R}^2-\mathrm{\pi }{r}^2 \\ =\mathrm{\pi }\left[{\left(126\right)}^2-{\left(105\right)}^2\right] \\ =\mathrm{\pi }\left(21\right)\left(231\right) \\ =15246{\mathrm{m}}^2 \end{gathered}$$