In 11/06 lecture notes, you said if A completely dominant over a. Should it be the ratio here?
That's a mistake. means complete dominance of A over a. (Or, as you say, is equivalent.) "Complete dominance" simply means that you cannot distinguish two copies vs. one copy of the dominant gene, which in turn implies that the genotypes with 1 or 2 copies should have the exact same phenotype (indistinguishable). Sorry for the mistake.