[tex]\it 6.\\ \\ R=3cm \Rightarrow ON = OM = 3cm\\ \\ MN=ON+OM=3+3=6cm[/tex]
[tex]\it 7.\\ \\ \left.\begin{aligned}OP=OM (raze) \Rightarrow \Delta OPM\ -\ isoscel\\ \\ \it \widehat{OPM} =60^o\end{aligned}\right\} \Rightarrow \Delta OPM\ -\ echilateral \Rightarrow \\ \\ \\ \Rightarrow \widehat{PMO}=60^o\\ \\ \stackrel\frown{NP}=2\cdot \widehat{PMO}=2\cdot60^o=120^o[/tex]
