Lunule (Ippocrate di Chio, V sec. a.C.)
https://latex.codecogs.com/png.image?\huge&space;\dpi{300}L=\frac{\pi}{2}\left(\frac{r}{\sqrt{2}}\right)^2\!-\left(\pi\,\frac{r^2}{4}-\frac{r^2}{2}\right)=\frac{r^2}{2}=T
Information: Lunule (Ippocrate di Chio, V sec. a.C.)