Jawabanmu

2014-05-16T11:44:24+07:00
L alas dan tutup = 2 ( 12 + 16 ) 10 /2
                        = 280  cm^{2}

L1 = 16 x 18 = 288  cm^{2}

L2 = 10 x 18 = 180  cm^{2}

L3 = 12 x 18 = 216  cm^{2}

L4 =  \sqrt{84} x 18 = 18  \sqrt{4.21} = 36  \sqrt{21}

L total = ( 280 + 288 + 180 + 216 + 36  \sqrt{21}  cm^{2}
          = 1000 +  36  \sqrt{21}   cm^{2}