Find a basis for the orthogonal complement of the following subspaces of $\mathbb{R}^4$ : (a) the set of solutions to $-x+3 y-2 z+w=0 ;$ (b) the subspace spanned by $(1,2,-1,3)^T$, $(-2,0,1,-2)^T,(-1,2,0,1)^T ;(c)$ the kernel of the matrix in Exercise 4.4.13c; $(d)$ the coimage of the same matrix.