[tex]\textit{area of a sector of a circle}\\\\ A=\cfrac{1}{2}\theta r^2~~ \begin{cases} r=radius\\ \theta =\stackrel{radians}{angle}\\[-0.5em] \hrulefill\\ r=12\\ \theta =\frac{3\pi }{4} \end{cases}\implies \begin{array}{llll} A=\cfrac{1}{2}\left( \cfrac{3\pi }{4} \right)(12)^2\implies A=\cfrac{432\pi }{8} \\\\\\ A=54\pi \implies \stackrel{using~\pi =3.14}{A=169.56} \end{array}[/tex]
