Kak tolong ini gimana pakai cara ya kakak

Unsur-unsur Lingkaran

<AOC = 360° - 90° - 120°
<AOC = 150°

L AOC/L AOB = <AOC/<AOB
L AOC/30 = 150/90
L AOC/30 = 5/3
3 x L AOC = 5 x 30
3 x L AOC = 150
L AOC = 150/3
L AOC = 50 cm^2 (A).

*semoga membantu. sukses selalu ^_^