Consider the following four points on the plane: A = (5,3), B = (1,1), C = (1,2), D = (3,2). (a) Find the distance matrix Dusing Euclidean distance between points. (b) Construct the dendogram obtained using single-linkage (you can do it by hand or using code) and compare the clusters you see to those obtained with K-means using two clusters (done in class).