tolong di jawab no.15,17,19,dan 20 ya........

JAWAB
15). Luas permukaan = luas selimut kerucut + luas selimut tabung + luas alas tabung = πrs + 2πrt + πr² = πr(s+2t+r). (B dan D sama)

17). Luas permukaan
★Luas ½ bola = 2πr² = 2×3,14×3² = 56,52 dm²
★Selimut tabung = 2πrt = 2×3,14×3×9 = 169,56 dm²
★Selimut kerucut = πrs = 3,14×3×5 = 47,1 dm²
Jadi Luas permukaan = 56,52+169,56+47,1 = 273,18 dm². (D)

19). Volume bola = 36π m³
⇨ (4/3)πr³ = 36π
⇨ (4/3)r³ = 36
⇨ 4r³ = 108
⇨ r³ = 27
⇨ r = 3 dm

Luas permukaan = 4πr² = 4×π×3² = 36π m². (C)

20). Rusuk = diameter = 12 cm
Maka jari-jari = 12/2 = 6 cm

Volume = (4/3)πr³ = (4/3)×3,14×6³ = 288×3,14 = 904.32 cm³. (A)