Jawabanmu

2014-05-11T19:36:19+07:00
540 = 12 X 5 / 2 x t
540 / 30 = t
t = 16 cm
L sisi tegak (16 x 12) +(16 x 5) + (16x13) = 192 + 80 + 208 = 480 cm2