[tex]\bf 1.\\ \\ \it a)\ L_c=d\cdotpi=6\cdot\pi=6\pi\ cm\\ \\ b)\ \ R=d:2=6:2=3\ cm\\ \\ \mathcal{A}=\pi R^2=\pi\cdot3^2=9\pi\ cm^2\\ \\ c)\ \ OD=\dfrac{17}{3}=5\dfrac{2}{3}>3=R \Rightarrow D-\ \ exterior\ \ cercului.\\ \\ d)\ \ d(a,\ O)=\sqrt{37}-3>\sqrt{36}-3=6-3=3=R \Rightarrow a\ - exterioar\breve a\ cercului.[/tex]
2.
[tex]\it (12,\ \ 16,\ \ 20)\ -\ triplet\ pitagoreic\ \Rightarrow ipotenuza=20cm\\ \\ R=ipotenuza:2=20:2=10\ cm[/tex]
