Penjelasan dengan langkah-langkah:

SERBA SERBI BALOK

1. p : l : t = 5 : 3 : 2

Volume = p × l × t

810 = 5s × 3s × 2s

810 = 30s³

s³ = 810

30

s³ = 27

s³ = 3³

s = 3

Luas permukaan = 2 × (p×l + p×t + l×t)

= 2 × (5×3×3×3 + 5×3×2×3 + 3×3×2×3)

= 2 × (15×9 + 15×6 + 9×6)

= 2 × (135 + 90 + 54)

= 2 × 279

= 558 cm² ✔

2. p : l : t = 3 : 2 : 1

Panjang rusuk = 4 × (p + l + t)

96/4 = 3s + 2s + s

24 = 6s

s = 24/6

s = 4

Volume = p × l × t

Volume = 3×4 × 2×4 × 1×4

Volume = 12 × 8 × 4

Volume = 96 × 4

Volume = 384 cm³ ✔

3. p : l : t = 3 : 5 : 7

Luas permukaan = 2 × (p×l + p×t + l×t)

774 = 2 × (3s×5s + 3s×7s + 5s×7s)

774/2 = 15s² + 21s² + 35s²

387 = 71s²

s² = 387

71

s = √5,45

s = 2,33

Panjang rusuk = 4 × (p + l + t)

= 4 × (3×2,33 + 5×2,33 + 7×2,33)

= 4 × (6,99 + 11,65 + 16,31)

= 4 × 34,95

= 139,8 cm ✔