Question

Keliling persegi panjang 54 cm. Jika p:l = 5:4
tentukan luas persegi panjang tersebut

Answer 1

DIK :
k = 54 cm
p : l = 5 : 4
maka :
K = 2 x (p+l)
54 = 2 x (5x + 4x)
54 = 2 x (9x)
54 = 18x
 x  = 54/18
 x  = 3 cm

jadi :
panjang = 5 x 3 = 15 cm
lebar = 4 x 3 = 12 cm

L = p x l
  = 15 x 12
  = 180 cm²

Answer 2

K = 54 cm
p:l = 5:4
2p:2l = 10:8
2p = 10/18 × 54cm
2p = 30cm
p = 30cm/2 = 15
2l = 8/18 × 54cm
2l = 24cm
l = 24cm/2 = 12cm
Luas = 15cm × 12cm = 180 cm^2