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28.C.1.536 29.B.12.320 30.D.9.600

28. L permukaan = sisi² × 6
= 16² × 6 = 1536cm² (C)

29. V = πr²t
= 22/7 × 14² × 20 = 12320cm² (B)

30. V.total = V1 + V2
V1 = 12×32×20 = 7680cm²
V2 = [(18-12)×20/2]×32 = 60×32 = 1920cm²
V.total = 7680 + 1920 = 9600cm² (D)