4.10 Let H be a set of at least three half-planes with a non-empty intersection such that not all bounding lines are parallel. We call a half-plane h E H redundant if it does not contribute an edge to nH. Prove that for any redundant half-planeh E H there are two half-planes,h" e H such that h' nh" Ch. Give an O(nlogn) time algorithm to compute all redundant half-planes