Jawabanmu

2014-05-25T19:00:55+07:00
L = 1/2 x d1 x d2
81 = 1/2 x 18 x (2x + 3)
2x + 3 = 81 x 2 / 18
2x + 3 = 9
2x = 9 - 3
2x = 6
x = 3

d2 = 2x + 3
     = 2(3) + 3
     = 6 + 3 = 9