okay so here's the problem that i found on the net...
"in the picture, AD is angle bisector if AB + AD = CD and AD + AC = BC ,
angle ACB = 20 degree,"
find angle ABC
here's the link to the picture (http://img694.imageshack.us/img694/6562/pb3.png)
and there are hints onto solving this problem as well... but i still can't doooo it.
"AD is a bisector implies
AB : AC = area(ABD) : area(ADC) = BD : DC
Use this to express BC/AB and hence cos(angle ACB) in
terms of k = AC/AB. Now, what is sin(angle ABC) in terms
of k and sin(angle ACB)?"