NCERT Solutions for Exercise 5.2 Class 9 Maths Chapter 5 - Introduction To Euclid's Geometry

NCERT Solutions for Exercise 5.2 Class 9 Maths Chapter 5 - Introduction To Euclid's Geometry

Edited By Safeer PP | Updated on Jul 18, 2022 02:14 PM IST

The topic of Euclid's postulate, specifically its fifth postulate, is covered in NCERT Solutions for Class 9 Maths exercise 5.2. Euclid's Geometry is the study of geometry based on undefined words such as points, lines, and planes of flat spaces, which was developed by Euclid, the Father of Geometry. In exercise 5.2 Class 9 Maths, Euclid's Euclid's geometry discussed the shape, size, and position of solid shapes such as the surface, straight or curved lines, points, and so on… Geometrically, there are 5 Euclid’s postulates They are,

• Postulate -1: A line segment is often drawn for any two given points.

• Postulate -2: A-line segments are often extended in either direction to make a line

• Postulate -3: To explain a circle with any centre and radius, that's a circle that is often drawn with any centre and any radius.

• Postulate -4: All right angles are proportional to one another.

• Postulate -5: If two lines are intersected by a third in such a way that the total of the inner angles on one side is less than two right angles, then the two lines will intersect endlessly on that side.

NCERT solutions for Class 9 Maths chapter 5 exercise 5.2 are made up of two questions that are based on Euclid's fifth postulate. In this Class 9 Maths chapter 5 exercise 5.2, the ideas connected to Euclid's Geometry are thoroughly discussed. Along with NCERT book Class 9 Maths chapter 5 exercise 5.2 the subsequent exercises also are present.

Introduction To Euclid's Geometry Class 9 Chapter 5 Exercise: 5.2

Q1 How would you rewrite Euclid’s fifth postulate so that it would be easier to understand?

Answer:

Euclid's 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.

1640082956556 Now, in an easy way
Let the line PQ in falls on lines AB and CD such that the sum of the interior angles 1 and 2 is less than 180° on the left side of PQ. Therefore, the lines AB and CD will eventually intersect on the left side of PQ.

Q2 Does Euclid’s fifth postulate imply the existence of parallel lines? Explain.

Answer: 1640082975160 According to Euclid's 5 postulates, the line PQ falls on lines AB and CD such that the sum of the interior angles 1 and 2 is less than 180° on the left side of PQ. Therefore, the lines AB and CD will eventually intersect on the left side of the PQ
Now,
If \angle 1+\angle 2 = 180\degree then, the line never intersects with each other.
Therefore, we can say that lines AB and CD are parallel to each other


More About NCERT Solutions for Class 9 Maths Exercise 5.2

Class 9 Maths chapter 5 exercise 5.2, The fifth postulate of Euclid geometry states that if any straight line falling on two straight lines produces interior angles on the same side of it that are less than two right angles when added together, then the two straight lines will meet on the side on which the sum of angles is less than two right angles if produced indefinitely.

Euclid proposed the fifth postulate. John Playfair's most recent version of Euclid's fifth postulate. Provided a line and a point not on it in a plane, he claims that only one line parallel to the given line can be traced through the point. This fifth postulate is commonly referred to as the parallel postulate since it is based on the uniqueness of parallel lines.

Also Read| Introduction To Euclid's Geometry Class 9 Notes

Benefits of NCERT Solutions for Class 9 Maths Exercise 5.2

• Through NCERT solutions for Class 9 Maths exercise 5.2, we will easily comprehend Euclid’s fifth postulate and these questions will assist us in mastering the principles of Euclid's geometry.

• If we look at the NCERT solution for Class 9 Maths chapter 5 exercise 5.2, we can easily remember all important terms introduced in Euclid’s geometry.

• For solving the questions of exercise 5.2 Class 9 Maths, we need to memorize the definitions and theorems clearly to understand and reinforce their knowledge. This may help gain a deep understanding of this topic.

Frequently Asked Questions (FAQs)

1. What is the fifth Euclid's postulate, according to NCERT solutions for Class 9 Maths chapter 5 exercise 5.2 ?

Postulate -5 indicates that if two lines are crossed by a third in such a way that the total of the inner angles on one side is less than two right angles, the two lines will intersect on that side if produced indefinitely, according to NCERT solutions for Class 9 Maths chapter 5 exercise 5.2.

2. The equivalent version of Euclid’s fifth postulate given by __________ .

The equivalent version of Euclid’s fifth postulate was given by John Playfair. 

3. State the Euclid’s fifth postulate which was given by John Playfair.

John Playfair states that in a plane, given a line and a point not on it, at most one line parallel to the given line can be drawn through the point.

4. Fifth postulate is popularly known as the __________

The fifth postulate is popularly known as the parallel postulate.

5. According to NCERT solutions for Class 9 Maths chapter 5 exercise 5.2 , why is the fifth postulate popularly known as the parallel postulate?

The fifth postulate is popularly known as the parallel postulate because it has been provided on the basis of the uniqueness of parallel lines. 

6. Who introduced Euclid’s fifth postulate for the first time?

Euclid’s fifth postulate was introduced by Euclid.

7. Euclid is known as the "Father of ______ ."

Euclid, the Father of Geometry, is the answer.

8. According to NCERT solutions for Class 9 Maths chapter 5 exercise 5.2 , define parallel lines.

According to NCERT solutions for Class 9 Maths chapter 5 exercise 5.2 , The lines which never intersect each other and are always at a constant distance perpendicular to each other are known as parallel lines. 

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A block of mass 0.50 kg is moving with a speed of 2.00 ms-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is

Option 1)

0.34\; J

Option 2)

0.16\; J

Option 3)

1.00\; J

Option 4)

0.67\; J

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1 m 1000 times.  Assume that the potential energy lost each time he lowers the mass is dissipated.  How much fat will he use up considering the work done only when the weight is lifted up ?  Fat supplies 3.8×107 J of energy per kg which is converted to mechanical energy with a 20% efficiency rate.  Take g = 9.8 ms−2 :

Option 1)

2.45×10−3 kg

Option 2)

 6.45×10−3 kg

Option 3)

 9.89×10−3 kg

Option 4)

12.89×10−3 kg

 

An athlete in the olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range

Option 1)

2,000 \; J - 5,000\; J

Option 2)

200 \, \, J - 500 \, \, J

Option 3)

2\times 10^{5}J-3\times 10^{5}J

Option 4)

20,000 \, \, J - 50,000 \, \, J

A particle is projected at 600   to the horizontal with a kinetic energy K. The kinetic energy at the highest point

Option 1)

K/2\,

Option 2)

\; K\;

Option 3)

zero\;

Option 4)

K/4

In the reaction,

2Al_{(s)}+6HCL_{(aq)}\rightarrow 2Al^{3+}\, _{(aq)}+6Cl^{-}\, _{(aq)}+3H_{2(g)}

Option 1)

11.2\, L\, H_{2(g)}  at STP  is produced for every mole HCL_{(aq)}  consumed

Option 2)

6L\, HCl_{(aq)}  is consumed for ever 3L\, H_{2(g)}      produced

Option 3)

33.6 L\, H_{2(g)} is produced regardless of temperature and pressure for every mole Al that reacts

Option 4)

67.2\, L\, H_{2(g)} at STP is produced for every mole Al that reacts .

How many moles of magnesium phosphate, Mg_{3}(PO_{4})_{2} will contain 0.25 mole of oxygen atoms?

Option 1)

0.02

Option 2)

3.125 × 10-2

Option 3)

1.25 × 10-2

Option 4)

2.5 × 10-2

If we consider that 1/6, in place of 1/12, mass of carbon atom is taken to be the relative atomic mass unit, the mass of one mole of a substance will

Option 1)

decrease twice

Option 2)

increase two fold

Option 3)

remain unchanged

Option 4)

be a function of the molecular mass of the substance.

With increase of temperature, which of these changes?

Option 1)

Molality

Option 2)

Weight fraction of solute

Option 3)

Fraction of solute present in water

Option 4)

Mole fraction.

Number of atoms in 558.5 gram Fe (at. wt.of Fe = 55.85 g mol-1) is

Option 1)

twice that in 60 g carbon

Option 2)

6.023 × 1022

Option 3)

half that in 8 g He

Option 4)

558.5 × 6.023 × 1023

A pulley of radius 2 m is rotated about its axis by a force F = (20t - 5t2) newton (where t is measured in seconds) applied tangentially. If the moment of inertia of the pulley about its axis of rotation is 10 kg m2 , the number of rotations made by the pulley before its direction of motion if reversed, is

Option 1)

less than 3

Option 2)

more than 3 but less than 6

Option 3)

more than 6 but less than 9

Option 4)

more than 9

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