(1 point) For each of the following, factor the matrix A into a product QDQT where Q is orthogonal and D is diagonal.
(a) A=[[7,1,1],[1,5,3],[1,3,5]]
D=[[8,0,0],[0,3,0],[0,0,1]]
(b) A=[[4,-2,2],[-2,3,-3],[2,-3,3]]
D=[[8,0,0],[0,3,0],[0,0,1]]
LS: Given a symmetric matrix A, I can orthogonally diagonalize A.