placate vs rid

placate

verb
  • To calm; to bring peace to; to influence someone who was furious to the point that they become content or at least no longer irate. 

rid

verb
  • To free (something) from a hindrance or annoyance. 

adj
  • Released from an obligation, problem, etc. (usually followed by of). 

How often have the words placate and rid occurred in a corpus of books? (source: Google Ngram Viewer )