Răspuns :
[tex]\it L_c=2\pi R=8\pi \Big|_{:2\pi} \Rightarrow R=4\ cm\\ \\ \mathcal{A}_{disc}=\pi R^2=\pi\cdot4^2=16\pi\ cm^2[/tex]
[tex]\it L_c=2\pi R=8\pi \Big|_{:2\pi} \Rightarrow R=4\ cm\\ \\ \mathcal{A}_{disc}=\pi R^2=\pi\cdot4^2=16\pi\ cm^2[/tex]