Class 9 Maths - Introduction to Euclid's Geometry

Introduction

Euclid's Geometry is based on axioms, postulates, and theorems that describe the fundamental properties and relations of geometric figures.

Important Points

Important Axioms & Postulates

1. Things which are equal to the same thing are equal to one another.
2. If equals are added to equals, the wholes are equal.
3. A straight line can be drawn from any point to any other point.
4. All right angles are equal to one another.
5. A circle can be drawn with any centre and radius.

Solved Examples

Example 1: State whether the statement "All right angles are equal" is an axiom or postulate.
Solution: It is a postulate.
Example 2: Which postulate allows us to draw a unique straight line through two points?
Solution: Euclid's First Postulate.
Example 3: If equals are subtracted from equals, the remainders are equal – Is it an axiom or postulate?
Solution: Axiom.
Example 4: Draw a circle with centre O and radius 5 cm. Which postulate is applied?
Solution: Postulate 3.
Example 5: Identify whether "A straight line can be produced indefinitely" is an axiom or postulate.
Solution: Postulate.

Practice Questions

  1. Name the book written by Euclid containing his work on geometry.
  2. Define an axiom with one example.
  3. State Euclid’s first postulate.
  4. Write any two axioms of Euclid.
  5. Explain the difference between axioms and postulates.