Postulate 1:

A straight line may be drawn from any one point to any other point.

The postulate says that a line passes through two point.

But, it does not say that only one line passes through 2 distinct points .

So, we make an axiom of it -  Axiom 5.1

Axiom 5.1.jpg

Postulate 2:

Terminated line means line segment can be extended from either

side to form a lines.


Here, Line AB can be extended from both sides


Postulate 3:

A circle can be drawn with any center and any radius

Eg: Circle of radius 1.5 cm & centre (0, 0)

      Circle of radius 2 cm & centre (0, 0)

      Circle of radius 1 cm & centre (1, 1)

postulates 3.jpg

Postulate 4:

All right angles are equal to one another .

postulates 4.jpg

Here, ∠ B = ∠ Q = 90°


Postulate 5:

If a straight line falling on two straight lines makes the interior

angles on the same side of it taken together less than two right angles, then the

two straight lines, if produced indefinitely, meet on that side on which the sum of

angles is less than two right angles

We discuss more about it in Ex 5.2, 1

  1. Chapter 5 Class 9 Introduction to Euclid's Geometry
  2. Concept wise
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Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 7 years. He provides courses for Mathematics and Science from Class 6 to 12. You can learn personally from here