[tex]\bf \textit{area of a sector of a circle}\\\\
A=\cfrac{\theta\pi r^2}{360}\qquad
\begin{cases}
\theta=\textit{angle in degrees}\\
r=radius=\frac{diameter}{2}\\
----------\\
\theta=170\\
diameter=9.1\\
r=\frac{9.1}{2}=4.55
\end{cases}\implies A=\cfrac{170\cdot \pi \cdot 4.55^2}{360}[/tex]
