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a b -b awill commute with the general 2-D rotation matrix (rotations about O)
M = 1 k R = cos(A) -sin(A) N = 1 0 0 1 sin(A) cos(A) 0 -1and I as the 2x2 identity matrix, prove that:
A = 1 0 B = 0 1 N = 0 -i 0 -1 1 0 i 0and I as the 2x2 identity matrix, prove that: