2. Let Si and $2 be two hyperplanes in R" defined by Si=(xEV(a,x) =bi}, S2 = taEV | (a2,x) = b2}. Let y ( R" be given. We consider the projection of y onto Sin S2, i.e., the solution of min le - yl|2. (1) ccSins2 Prove that z is a solution of (1) if and only if z e S, n S, and (z -y,z-x) =0, VESinS. (2)