Solution
= Solution
Set $Q=I-P$. Since $Q^2=I-2P+P^2=I-P=Q$, the previous result applies to this <projector> and gives $\mathcal N(Q)=\mathcal C(I-Q)$. Substituting $Q=I-P$ proves \b[$\mathcal N(I-P)=\mathcal C(P)$]. These are the <kernel-image identities for complementary projectors>.