declare vs demonstrate

declare

verb
  • To assert or announce formally, officially, explicitly, or emphatically. 

  • To make outstanding debts, e.g. taxes, payable. 

  • To show one's cards in order to score. 

  • To explicitly establish the existence of (a variable, function, etc.) without necessarily describing its content. 

  • For a constituency in an election to officially announce the result 

  • For the captain of the batting side to announce the innings complete even though all batsmen have not been dismissed. 

  • To inform government customs or taxation officials of goods one is importing or of income, expenses, or other circumstances affecting one's taxes. 

demonstrate

verb
  • to show, display, or present; to prove or make evident 

  • to show the steps taken to create a logical argument or equation. 

  • to show how to use (something). 

  • to participate in or organize a demonstration. 

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