[tex]\bf \textit{area of a sector of a circle}\\\\ A=\cfrac{\theta \pi r^2}{360}~~ \begin{cases} r=radius\\ \theta =angle~in\\ \qquad degrees\\[-0.5em] \hrulefill\\ \theta =90\\ r=6 \end{cases}\implies A=\cfrac{(90)(\pi )(6)^2}{360} \\\\\\ A=\cfrac{3240\pi }{360}\implies A=9\pi \implies A\approx 28.2743[/tex]
