Important Formulas: Introduction to Euclid's Geometry | Mathematics (Maths) Class 9 PDF Download

Important Formulas

• Euclid: Euclid a Greek mathematician is called the Father of Geometry
• Euclid Geometry definition: 
  1) A point is that which has no part
  2) A line is breath less and has length only
  3) The end of a line is points
  4) A straight line is a tine which lies evenly with the points on itself
  5) A surface is that which has length and breadth only
  6) The edges of a surface are lines
  The definitions of line, point, plane explained by Euclid is not accepted by the Mathem
• Axioms or Postulates: Axioms or Postulates are assumptions which are obvious universal truths. They are not proved
• Theorems: They are statements which are proved using axioms/postulates, definition, previously proved statement and deductive reasoning
• Euclid Axioms: 
  1) Things which are equal to same things are equal to one another If x = z, y = z then x = y
  2) If equals are added to equals, the wholes are equal x = y ⇒ x + z = y + z
  3) If equals are subtracted from equals, the remainders are equal X = y ⇒ x - z = y - z
  4) Things which coincide with one another are equal to one another
  5)The whole is greater than the part.