bila jari jarinya 5cm ,maka tentukan luas dan kelilingnya

[tex]luas = \pi {r}^{2} \\ = 3.14 \times 5 \times 5 \\ = 78.5 {cm}^{2} \\ \\ keliling = \pi \times d \\ = 3.14 \times 10 \\ = 31.4cm[/tex]