Pusing nih tolong jawab

dik:
α = 144°
panjang busur AB = 50,24 cm

dit: r

jawab:
panjang busur AB = α/360° × 2πr
50,24 = 144°/360° × 2 × 3,14 × r
50,24 = 2/5 × 6,28 × r
50,24 = 2,512 × r
r = 50,24 ÷ 2,512
r = 20 cm ⇒ jwban.