now, let's notrice something, that AO = OC, namely those two are just the radius.
[tex]\bf \textit{area of a segment of a circle}\\\\ A=\cfrac{r^2}{2}\left( \cfrac{\pi \theta }{180}~~-~~sin(\theta ) \right)~~ \begin{cases} r=radius\\ \theta =angle~in\\ \qquad degrees\\[-0.5em] \hrulefill\\ r=10.4\\ \theta =120 \end{cases} \\\\\\ A=\cfrac{10.4^2}{2}\left( \cfrac{\pi (120)}{180}~~-~~ sin(120^o) \right)[/tex]
[tex]\bf A=\cfrac{108.16}{2}\left( \cfrac{3\pi}{2}~~-~~\cfrac{\sqrt{3}}{2} \right)\implies A=54.08\left( \cfrac{3\pi}{2}~~-~~\cfrac{\sqrt{3}}{2} \right) \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ ~\hfill A\approx~~208.011~\hfill[/tex]
