(1), a/(b+c)=b/(a+c)=k, then the application ratio property is (a+b+c)/(b+c) = (b+a+c) = k, then b+c=a+c, so a=c=3

So when a=b=c=3, k= 1/2.

(2), a/(b+c)=b/(a+c)=k, so a/(b+c)=-b/-(a+c)=k, so k =-65433.

So k has two values-1or 1/2.

K=- 1 or 1/2,

The rest is wrong! ! ! ! !

In fact, this topic is about the similar equality and combination properties of triangles, and mine can never be wrong.