Jawabanmu

2014-01-21T16:58:33+07:00
P = 81*2/ 4 = 40,5 m
l = 81*2/ 5 = 32,4 m
L = p*l = 40,5 m * 32,4 m = 218,70 m2
Jawaban paling cerdas!
2014-01-21T16:59:53+07:00
Kel = 2(p+l)
  81 = 2(5x+4x)
  81= 10x + 8x
  81 = 18x
    x=81/18
    x=9/2
    x= 4.5


p= 5x
   = 5 x 4.5
   = 22.5 cm

l= 4x
  = 4 x 4.5
  = 18 cm
 luas = p x l
       = 22.5 x 18
      = 405 cm^2



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