please tolong jawab pakai cara

[tex] \frac{sudut \: aob}{sudut \: cod} = \frac{luas \: oab}{luas \: ocd} \\ \frac{60}{105} = \frac{12}{luas \: ocd} \: (dikalikan \: silang) \\ 60 \times luas \: cod = 105 \times 12 \\ luas \: cod = \frac{1260}{60} \\ luas \: cod = 21 \: {cm}^{2} [/tex]