yg bisa bantu jwb , tolong ya :D

jadikan jawaban terbaik jika membantu
Berikan terima kasih

Gambar A

d = 2.r = 2(10) = 20cm
Panjang sabuk =
[Phi × d ]+ [4d] =
(3,14 × 20) + 4(20) =
62,8 + 80 =
142,8cm

Gambar b
d = 2.r = 2(14) = 28cm

Panjang sabuk =
(Phi × d) + 3d =
(22/7 × 28) + 3(28) =
88 + 84 =
172cm