set square vs trigon

set square

noun
  • A flat triangular piece of plastic or other material, having corners of precise angles, used in technical drawing 

  • A right angle tool used to determine if two surfaces join at a 90-degree angle, composed of two arms, usually made from metal. 

trigon

noun
  • A triangle. 

  • A trine; an aspect of two planets distant 120 degrees from each other. 

  • An ancient triangular harp of Oriental origin which had four strings and was often used for banquet music. Also called sabbeka, sackbut, sambuca. 

  • A division consisting of three signs. 

  • An old ball game played by three people standing in a triangular formation. 

  • The cutting region of the crown of an upper molar, usually the anterior part. 

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