https15postimgorgrzn1c3nbfimagepngSolutiona let the closed s

http://s15.postimg.org/rzn1c3nbf/image.png?

let the closed set A be = log(x) and let the set B be = - log(y)

now both x and y would be greated that 0 , but at no point in time they will be the same , as if they become the same then

the condition d(A,B) =0 will not be satisfied , as when x = y then the distance becomes finits or in orther words non zero.