Solution:EnragePlacate - to make somebody feel less angry about something.
Conciliate -To try to make a group of people less angry, especially in order to end a dispute.
Enrage - To make somebody very angry.
Propitiate- To make peace with somebody who is angry by trying to please them.
Appease - to make somebody calmer or less angry by agreeing to what he/she wants.
So,'Enrage' is the perfect antonym for "Placate".