Berapa luas daerah yg diarsir ??

Juring lingkaran = alpha / 360 × luas lingkaran
Jl= 120/360 × 22/7 × (21/2) × (21/2)
Jl = 1/3 × 22/7 × 21/2 × 21/2
Jl = 115,5 cm^2

Luas lingkaran = pi × r²
=22/7×21×21
=22×3×21
=1386