Jawabanmu

2014-05-06T22:38:57+07:00
P = 4 + l
t = 1/2 l
Lp = 1216 cm ^2
1216 = 2 (p x l + p x t + l x t)
1216 = 2 { ( 4 + l) l + ( 4 + l) 1/2 l + l x 1/2 l) }
1216 = 2 ( 4l + l ^2 + 2l + l ^2 / 2 + l ^2 / 2)
1216 = 8l + 2l ^2 + 4l + 2l ^2 / 2 + 2l ^2 / 2)
1216 = 12l + 2l ^2 + 4l ^2 / 2
1216 = 12l + 2l ^2 + 2l ^2
1216 = 12l + 4l ^2
1216 - 12l = 4l ^2
.....hitung manual..... -----> l = 16 cm
p = 4 + l = 4 + 16 = 20 cm
t = 1/2 l = 1/2 x 16 = 8 cm
pembuktian:
1216 = 2 (p x l + p x t + l x t)
1216 = 2 (20 x 16 + 20 x 8 + 16 x 8)
1216 = 2 (320 + 160 + 128)
1216 = 2 x 608
1216 = 1216

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