Final answer:
Napoleon got his idea about the three consuls approved by the people through a nationwide referendum and plebiscite in which the male population voted in support of his title as Emperor of France.
Step-by-step explanation:
Napoleon got his idea about the three consuls approved by the people by holding a nationwide referendum. He called for a plebiscite, which is a vote of the entire male population, to support his title of Emperor of France. The plebiscite resulted in a landslide victory, solidifying his power and authority.