If x, y and z are the lengths of the sides of a triangle and k=(x^2+y^2+z^2)/(xy+yz+xz) which of the following best describes k?

1) 0 < k < 1/2
2) 1 ≤ k < 3/2
3) 1 ≤ k ≤ 2
4) 1 ≤ k < 2