The sector area is[tex] A=\frac{R^2\alpha}{2}[/tex].
You have [tex]A=125.6 \text{ square centimeters} \\ R=8 \text{ centimeters}[/tex],
then
[tex] 125.6 =\frac{8^2\alpha}{2}\rightarrow \alpha= \frac{125.6\cdot 2}{64} =3.925[/tex].
Since [tex]3.925:3.14=1.25= \frac{5}{4} [/tex] you can obtain that [tex]\alpha= \frac{5\pi}{4} [/tex]=225^{\circ}.
