Let Q be an m à m orthogonal matrix. (a) Prove that for any given vectors u and v in R m, the angle between u and v is the same as the angle between Qu and Qv. (b) Prove that IIQII2 = 1. (c) Give an example 2 à 2 orthogonal matrix Q, such that IIQII does not equal 1 and IIQIIâ does not equal 1. (d) Prove that IIQAII2 = IIAII2, for any m à m matrix A.