< BOC = 128 derajat
Luas juring OAB = 30 dm2
Luas juring OBC adalah
< AOB = 80 derajatar
<AOB/<BOC = j.AOB/j.BOC
80/128 = 30/x
80x = 30 . 128
8x = 3 . 128
x = 13 . 8 . 3 /8
x = 39
< BOC = 128 derajat
Luas juring OAB = 30 dm2
Luas juring OBC adalah
< AOB = 80 derajatar
<AOB/<BOC = j.AOB/j.BOC
80/128 = 30/x
80x = 30 . 128
8x = 3 . 128
x = 13 . 8 . 3 /8
x = 39