I am trying with no luck to prove:
Let (X,d) be a metric space and A a non-empty subset of X. For x,y in X, prove that
d(x,A) < d(x,y) + d(y,A)
I am trying with no luck to prove:
Let (X,d) be a metric space and A a non-empty subset of X. For x,y in X, prove that
d(x,A) < d(x,y) + d(y,A)