Jawabanmu

2014-06-07T15:06:26+07:00
L = 1/2 x a x t 
104 = 1/2 x (x-2) x 8
104 = 4 x (x-2)
104 = 4x - 8
112 = 4x
x = 28 cm .

Alas = 28 cm - 2cm = 26 cm 

maaf kl salah .. semoga membantu ...:)
2014-06-07T16:03:12+07:00
L= 1/2.a.t                        alas =28-2
104=1/2.(x-2) .8                    =26 cm
104= (x-2) .4
104/4 =x-2
26 =x-2
x=26+2
x=28