Crossword: Triangle

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Across
  1. 3. a three-sided polygon that consists of three edges and three vertices.
  2. 4. a book that is collection of definitions, postulates, propositions, and mathematical proofs of the propositions
Down
  1. 1. the perpendicular drawn from the vertex of the triangle to the opposite side​.
  2. 2. the bottom line of a triangle.
  3. 5. he was an ancient Greek mathematician active as a geometer and logician. Considered the "father of geometry"