3. In the following question assume that you are given a function EDist (pointl, point2) which calculates the distance between point!-(P1,P2) and point2-(P3,P4), where pl, p2,P3, and p4 are integers (pointl, and point2 are two points in the Euclidian plane.) Assume that EDist is correct (a) Give an appropriate loop invariant for the purpose of proving the partial correctness of the algo- rithm with respect to its given specification. (b) Use your loop invariant from part (a) to prove the partial correctness of Algorithm3 with respect to the given specification. (c) Prove your loop invariant Precondition: A is a list of points in the Euclidian space, each given as a pair of integers, and len(A) 1, and 0