Resposta :
[tex]A = \dfrac{ \theta\pi {r}^{2} }{ {360}^{ \circ} } \\ \\ A = \dfrac{ 90 \cdot 3,14 \cdot{10}^{2} }{ {360}^{ \circ} } \\ \\ A = 78,5 \: {cm}^{2} [/tex]
[tex]A = \dfrac{ \theta\pi {r}^{2} }{ {360}^{ \circ} } \\ \\ A = \dfrac{ 90 \cdot 3,14 \cdot{10}^{2} }{ {360}^{ \circ} } \\ \\ A = 78,5 \: {cm}^{2} [/tex]