1. sebuah balok berukuran panjang=20 cm,lebar=12 cm, tinggi= 9 cm. jumlah panjang rusuk balok tersebut adalah..... 2. perbandingan panjang,lebar dan tinggi sebu

1. diketahui :
panjang (p) = 20
lebar (l) = 12
tinggi (t) = 9

panjang rusuk :
= 4(p + l + t)
= 4 (20 + 12 + 9)
= 4 (41)
= 81 cm


2. perbandingan p : l : t = 5 : 3 : 2
misal :
p = 5x , l = 3x , t = 2x

Volume :
p l t = 810
5x . 3x . 2x = 810
30x³ = 810
x³ = 27
x = 3

Luas permukaan :
= 2 (pl + pt + lt)
= 2 (5x. 3x + 5x . 2x + 3x . 2x)
= 2 (15x² + 10x² + 6x²)
= 2 (31x²)
= 62 x²
= 62 . 3²
= 62 . 9
= 558 cm² 
 
 

1. JPR = 4(12+20+9)
= 4(41)
= 164cm

2. Volume = p.l.t
810 = 5x.3x.2x
810 = 30x*3
810/30 = x*3
akar3dari27 = x
3 = x
panjang =5x
= 5.3
= 15cm
lebar = 3x
= 3.3
= 9cm
tinggi = 2x
= 2.3
= 6cm
Luas Permukaan = 2(pl.pt.lt)
= 2(15.9+15.6+9.6)
= 2(135+90+54)
= 2(279)
= 558cm*2