tolong bantu jawab no. 7

diketahui:
r1 = 1+2 = 3cm
r2 = 2cm
sudut AOB = 72°

ditanya:
L.diarsir

dijawab:
L.1 = 1/5×3,14×3²
L.1 = 5,652cm²

L.2 = 1/5×3,14×2²
L.2 = 2,512cm²

L.diarsir = L.1-L.2
L.diarsir = 5,652-2,512
L.diarsir = 3,14cm² = 3 1/7cm² (B)