Diketahui panjang busur 22cm sudut busat 120° berapa jari jarinya

P busur = 120 / 360 × 2. phi. r

22 = 1/3 × 2 . 22/7 . r

22 = 44/21 . r

22×21 = 44r

r = 10.5

maaf kalo salah

Keliling = (360/120) x 22
             = 3 x 22
             = 66 cm

K = 2πr
66 = 2 x 22/7 x r
66 = 44/7 r
r = 66 x 7/44
r = 10,5 cm