Jawabanmu

2014-05-29T13:51:29+07:00
  k=2.(p+l)
64=2.(5x+3x)
64=2.8x
64=16x
  x= 64
       16
   x=4cm
-p            - l
 5x            3x
 5.4            3.4
 20 cm        12cm
L=p.l
   20.12
   240cm²
2014-05-29T13:53:16+07:00
K=2p+2l
64=2.5x + 2.3x
64=10x+6x
64=16x
 \frac{64}{16} = x
4=x

Panjang = 5.4 = 20 cm
Lebar = 3.4 = 12 cm

L=p.l
L=20.12
L=240 cm²
K = 2 (p+l) -->> p : l = 5y : 3y
64 = 2(5y + 3y)
64 = 2 x 8y
8y = 64 : 2 = 32
y = 32 : 8 = 4
panjang = 5y = 5x4 = 20 cm
lebar = 3y = 3x4 =12 cm
Luas = p xl
= 20cm x 12cm
= 240 cm²