Hi Manjit,

Euclid has some axioms and postulates.

Axioms means assumptions.

Postulates means assumptions related to geometry.

In the NCERT Book, we have 5 postulates and some axioms.

There is nothing as Axiom 4, were you asking Postulate 4?

Here are the axioms and postulates as written from Chapter 5 Class 9 Euclid GeometrySome of Euclid’s axioms

Some of Euclid’s axioms were :

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. If equals are subtracted from equals, the remainders are equal.
4. Things which coincide with one another are equal to one another.
5. The whole is greater than the part.
6. Things which are double of the same things are equal to one another.
7. Things which are halves of the same things are equal to one another.

Euclid’s postulates were :Postulate

Postulate 1 : A straight line may be drawn from any one point to any other point.Postulate 2 : A terminated line can be produced indefinitely.

Postulate 2 : A terminated line can be produced indefinitely.

Postulate 3 : A circle can be drawn with any centre and any radius.

Postulate 4 : All right angles are equal to one another.

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