sebuah balok mempunyai volume 7.680cm³ dan perbandingan panjang :lebar:tinggi adalah 6:4:5. luas permukaan balok tersebut

Bangun Ruang Sisi Datar.

V = plt
7680 = (6x)(4x)(5x)
7680 = 120x³ → x = 4

L = 2(pl + pt + lt)
   = 2 [(6x)(4x) + (6x)(5x) + (4x)(5x)]
   = 2 (74x²)
   = 2 (74)(4)² = 2368 cm²

P = 6 × n = 6n

l = 4 × n = 4n

T = 5 × n = 5n


V = P × l × T

7.680 = 6n × 4n × 5n

7.680 = 120n^3

n^3 = 7.680 ÷ 120

n^3 = 64 (diakarkan pangkat 3)

n^3 = 4 cm


jdi


P = 6 × n = 6 × 4 = 24 cm

l = 4 × n = 4 × 4 = 16 cm

T = 5 × n = 5 × 4 = 20 cm


Jdi luasnya


L = 2 × (p×l + p×t + l×t)

= 2 × (24×16 + 24×20 + 16×20)

= 2 × (384 + 480 + 320)

= 2 × 1.184

= 2.386 cm^2