(a) Determine the basechange matrix in R2, when the old basis is the standard basis E(e1, e2) and the new basis is B = (e1 + e2, e1-e2). (b) Determine the basechange matrix in R", when the old basis is the standard basis E and the new basis is B = (en, en-1,..., e). (c) Let B be the basis of R2 in which v = e and v2 is a vector of unit length making an angle of 120 with v. Determine the basechange matrix that relates E to B.