contend vs take on

contend

verb
  • To struggle or exert oneself to obtain or retain possession of, or to defend. 

  • To be in opposition; to contest; to dispute; to vie; to quarrel; to fight. 

  • To be in debate; to engage in discussion; to dispute; to argue. 

  • To believe (something is reasonable) and argue (for it); to advocate. 

  • contend with: To try to cope with a difficulty or problem. 

take on

verb
  • To attempt to fight, compete with, or engage with. 

  • To assume or take responsibility for. 

  • To (attempt to) dribble round (an opposition player). 

  • To catch on, do well; to become popular. 

  • To obtain the services of (a person) in exchange for remuneration; to give someone a job. 

  • To begin to have or exhibit. 

  • To acquire, bring in, or introduce. 

  • To grieve or be concerned (about something or someone). 

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