Resposta:
[tex]\textsf{Leia abaixo}[/tex]
Explicação passo a passo:
[tex]\mathsf{A_{SEG} = A_{SET} - A_T}[/tex]
[tex]\mathsf{A_{SEG} = \dfrac{\Theta.\pi .r^2}{360\textdegree} - \dfrac{a.b.sen\:\Theta}{2}}[/tex]
[tex]\mathsf{A_{SEG} = \dfrac{45\textdegree.\pi .3^2}{360\textdegree} - \dfrac{3.3.sen\:45\textdegree}{2}}[/tex]
[tex]\mathsf{A_{SEG} = \dfrac{45\textdegree.\pi .9}{360\textdegree} - \dfrac{9}{2}\:.\:\dfrac{\sqrt{2}}{2}}[/tex]
[tex]\mathsf{A_{SEG} = \dfrac{45\textdegree.\pi .9}{360\textdegree} - \dfrac{9\sqrt{2}}{4}}[/tex]
[tex]\boxed{\boxed{\mathsf{A_{SEG} = \dfrac{9\pi}{8} - \dfrac{9\sqrt{2}}{4}\:cm^2}}}[/tex]