tolong jawab soal di bawah ini pasti kalian bisa satu aja soalnya

(A.) L = 60°/360° × π × r²
231 cm² = 1/6 × 22/7 × r²
231 cm² = 22/42 × r²
r² = 231 cm² ÷ 22/42
r² = 231 cm² × 42/22
r² = 441
r = √(441 cm²)
r = 21 cm

(B.) K = 60°/360° × 2 × π × r
K = 1/6 × 2 × 22/7 × 21 cm
K = 1/6 × 132 cm
K = 22 cm