Jawabanmu

2014-06-09T19:47:08+07:00
Berpelurus = 180 

7x + 5x = 180
  12x     = 180
    x       = 15

<a = 7 x 15 = 105
<b = 5 x 15 = 75
2014-06-09T19:47:22+07:00
Berpelurus : 180 derajat.
A : 180 . (7 : 12) = 105 derajat.
B : 180 . (5 : 12) = 75 derajat.