[tex]a) \: \: O = 2 \times \pi \: r \\ O = 2 \times \pi \: 5 = 31.42 \\ P = \pi \: r^{2} \\ P = \pi \: {5}^{2} = 78.54[/tex]
[tex]b) \: \: O = 2 \times \pi \: r \\ O = 2 \times \pi \: 10.2 = 64.09 \\ P = \pi \: r^{2} \\ P = \pi \: 10.2^{2} = 326.85[/tex]
