proposition: Lemma nrCC1_a3 : a'[^]2[-]b'[^]2 [=] a.
proof: Proof. unfold a', b' in |- *. apply eq_transitive_unfolded with (a'2[-]b'2). apply cg_minus_wd. apply sqrt_sqr. apply sqrt_sqr. unfold a'2, b'2 in |- *. unfold Half in |- *. rational. Qed.
imports: CoRN.complex.CComplex Coq.Arith.Wf_nat Coq.setoid_ring.ArithRing