Question

Perbandingan panjang, lebar , dan tinggi sebuah balok berturut - turut adalah 4 : 3 : 2.
Hitunglah ukuran balok tersebut, jika luas permukaannya 468 cm.

Answer 1

L = 2(PL + PT + LT)
468 cm² = 2( 4y.3y + 4y.2y + 3y.2y)
468 cm² = 2(12y² + 8y² + 6y²)
468 cm² = 2(26y²)
468 cm² = 52y²
y² = 468 ÷ 52
y² = 9
y = √9
y = 3

P = 4y
P = 4.3
P = 12

L = 3y
L = 3.3
L = 9

T = 2y
T = 2.3
T = 6

Answer 2

Luas      = 2 [ ( p x l ) + ( p x t ) + ( l x t ) ]
468 cm² = 2 [ ( 4y x 3y ) + ( 4y x 2y ) + ( 3y x 2y)
468 cm² = 2 [ 12y² + 8y² + 6y² ]
468 cm² = 2 [ 26y² ]
468 cm² = 52y²
y²          = 468/52
y²          = 9
y           = √9
y           = 3

p = 4y = 4(3) = 12 cm
l = 3y = 3(3) = 9 cm
t = 2y = 2(3) = 6 cm