Resposta :
Letra D
[tex]ac = \pi {r}^{2} \\ ac1 = \pi \times {30}^{2} = \pi \times 900 \\ ac2 = \pi \times {20}^{2} = \pi \times 400 \\ ac1 - ac2 = \pi \times (900 - 400) = \\ 500\pi \: {cm}^{2} [/tex]
Letra D
[tex]ac = \pi {r}^{2} \\ ac1 = \pi \times {30}^{2} = \pi \times 900 \\ ac2 = \pi \times {20}^{2} = \pi \times 400 \\ ac1 - ac2 = \pi \times (900 - 400) = \\ 500\pi \: {cm}^{2} [/tex]