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Lines and Angles Class 9 Notes CBSE Maths Chapter 6 (Free PDF Download)

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NCERT Class 9 Maths Revision Notes Chapter 6- Lines and Angles

Vedantu's comprehensive resource for Class 9 students studying NCERT Maths! We understand the significance of well-structured revision notes, and that's why we've meticulously crafted CBSE Class 9 Maths Chapter 6 revision notes. Our expert educators have designed these notes to align with the latest CBSE syllabus.


These downloadable PDF notes not only aid in your Class 9 exams but also serve as valuable preparation material for competitive exams like IIT, JEE, Olympiads, and more. With a focus on clarity and simplicity, our notes provide step-by-step guidance to tackle even the trickiest questions in the chapter. We're committed to making your learning journey smooth and effective.


To access these incredible resources, just click on the provided PDF link for Class 9 Maths Chapter 6 revision notes. Prepare smarter, aim higher, and excel in your academics and beyond!


Important Topics Covered in Class 9 Maths Chapter 6

  • Introduction

  • Basic Terms and Definition

  • Intersecting Lines and Non-Intersecting Lines

  • Pairs of Angles

  • Parallel Lines and Transversal Line

  • Lines Parallel to the Same Line

  • Angle Sum Property of a Triangle


Download CBSE Class 9 Maths Revision Notes 2024-25 PDF

Also, check CBSE Class 9 Maths revision notes for all chapters:


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Lines and Angles Class 9 Notes CBSE Maths Chapter 6 (Free PDF Download)
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Access Class 9 Mathematics Chapter 6 - Lines and Angles Notes

Geometrical Concepts

Point:

  • It is a precise position. 

  • It is a small dot with no length, width, or thickness, but it does have location, i.e. no magnitude. 

  • It is denoted by capital letters \[A,\text{ }B,\text{ }C,\text{ }O\] etc.

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Line Segment:

  • A line segment \[\overline{AB}\] is a straight path that connects two points \[A\]and \[B\]. 

  • It has a defined length and end points. (There is no width or thickness)

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Ray:

A ray is a line segment that can only be extended in one direction.


Line:

A line is formed when a line segment is stretched in both directions indefinitely.


Collinear Points:

Collinear points are defined as two or more points that are on the same line.

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Non-collinear Points:

  • Non-collinear points are those that do not lie on the same line.

  • Example: \[\text{A, B, C, D, E}\]

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Intersecting Lines:

  • Intersecting lines are two lines that have a common point.

  • The common point is called as the point of intersection.

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Concurrent Lines:

Concurrent lines are defined as two or more lines intersecting at the same point.

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Plane:

  • A plane is a surface on which every point of a line connecting any two points lies on that line.

  • Surface of a smooth wall, surface of a paper.

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Angles:

  • An angle is formed when two straight lines intersect at a point.

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  • It can be represented as \[\angle \text{AOB}\] or \[\text{A}\widehat{\text{O}}\text{B}\].

  • \[\text{OA}\] and \[\text{OB}\]are the arms of \[\angle \text{AOB}\].

  • The vertex of the angle \[\left( \text{O} \right)\] is defined as the place where the arms meet.

  • The amount of turning from one arm \[\text{OA}\] to other \[\text{OB}\] is called the measure of the angle \[\angle \text{AOB}\] and written as \[\text{m}\angle \text{AOB}\].

  • Degrees, minutes, and seconds are used to calculate an angle.

  • If a ray spins in an anticlockwise direction around its initial position and returns to its original position after one complete rotation, it has turned \[{{360}^{\circ }}\].

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\[1\] complete rotation is divided into \[360\] equal parts. 

Each part is \[{{1}^{{}^\circ }}\]. 

Each part \[\left( {{1}^{\circ }} \right)\] is divided into \[60\] equal parts where, each part measures \[1\] minute \[\left( 1' \right)\]. 

\[1'\] is divided into \[60\] equal parts where, each part measures \[1\] second \[\left( 1'' \right)\]

\[\text{Degrees }\to \text{ minutes }\to \text{ seconds}\]

\[{{1}^{\circ }}=60'\]

\[1'=60''\]

By recalling that the union of two rays forms an angle.

By observing the different type of angles in below figure, we conclude that

(Image will be Uploaded Soon)

  • \[\text{A}\widehat{\text{O}}\text{B}\] is an acute angle \[\left( {{\text{0}}^{\circ }}\text{  A}\widehat{\text{O}}\text{B  9}{{\text{0}}^{\circ }} \right)\]

  • \[\text{A}\widehat{\text{O}}\text{C}\] is a right angle \[\left( \text{an angle equal to 9}{{\text{0}}^{\circ }} \right)\]

  • \[\text{A}\widehat{\text{O}}\text{D}\] is an obtuse angle \[\left( \text{9}{{\text{0}}^{\circ }}\text{  A}\widehat{\text{O}}\text{D  18}{{\text{0}}^{\circ }} \right)\]

  • \[\text{A}\widehat{\text{O}}\text{E}\] is a straight angle \[\left( \text{an angle equal to 18}{{\text{0}}^{\circ }} \right)\]

  • \[\text{A}\widehat{\text{O}}\text{F}\] (measured in anti-clock wise direction) is a reflex angle \[\left( \text{18}{{\text{0}}^{\circ }}\text{  A}\widehat{\text{O}}\text{F  36}{{\text{0}}^{\circ }} \right)\]


Right Angle:

An angle whose measure is \[\text{9}{{\text{0}}^{\circ }}\] known as a right angle.

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Acute Angle:

An angle whose measure is less than one right angle (that is, less than  \[\text{9}{{\text{0}}^{\circ }}\]), known as an acute angle.

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Obtuse Angle:

An angle whose measure is more than one right angle and less than two right angles (that is less than \[\text{18}{{\text{0}}^{\circ }}\]and more than \[\text{9}{{\text{0}}^{\circ }}\]) known as an obtuse angle.

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Straight Angle:

An angle whose measure is \[\text{18}{{\text{0}}^{\circ }}\] known as a straight angle.

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Reflex Angle:

An angle whose measure is more than \[\text{18}{{\text{0}}^{\circ }}\]and less than \[\text{36}{{\text{0}}^{\circ }}\]is called a reflex angle.

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It can be written as \[\text{ref}\text{. }\angle \text{AOB}\].


Complete Angle:

An angle whose measure is \[\text{36}{{\text{0}}^{\circ }}\] called a complete angle. 

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Equal Angles:

When two angles have the same measure, they are said to be equal.


Adjacent Angles:

Adjacent angles are two angles that share a common vertex and a common arm and have their other arms on opposite sides of the common arm.

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\[O\] is the common vertex.

\[\text{A}\widehat{\text{O}}\text{B}\] and \[B\widehat{\text{O}}C\] are adjacent angles.

Arm \[\text{BO}\] separates the two angles.


Complementary Angles:

Complementary angles are those in which the total of the two angles is one right angle (that is \[\text{9}{{\text{0}}^{\circ }}\]).

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If the measure of 

\[\text{A}\widehat{\text{O}}C={{\text{a}}^{\circ }}\]

\[\text{C}\widehat{\text{O}}\text{B}={{b}^{\circ }}\], then

\[{{\text{a}}^{\circ }}+{{b}^{\circ }}={{90}^{\circ }}\]

Therefore, \[\text{A}\widehat{\text{O}}C\] and \[\text{C}\widehat{\text{O}}\text{B}\] are complementary angles.

\[\text{A}\widehat{\text{O}}C\] is complement of \[\text{C}\widehat{\text{O}}\text{B}\].


Supplementary Angles:

If the sum of two angles' measurements is \[\text{18}{{\text{0}}^{\circ }}\], they are said to be supplementary.


Example:

Angles measuring \[\text{13}{{\text{0}}^{\circ }}\]and \[\text{5}{{\text{0}}^{\circ }}\] are supplementary angles. 

Two supplementary angles are mutually beneficial.

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Vertically Opposite Angles:

Vertically opposing angles are generated when two straight lines intersects each other at a point and form pairs of opposite angles.

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Angles \[\angle 1\] and  \[\angle 3\], and angles \[\angle 2\] and \[\angle 4\] are vertically opposite angles.

Vertically opposite angles are always equal.


Bisector of an Angle

  • A ray or a straight line passing through the vertex of an angle is known as the Bisector of that angle if it divides the angle into two equal-sized angles.

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  • \[\text{B}\widehat{\text{O}}\text{C = C}\widehat{\text{O}}A\] and,

\[\text{B}\widehat{\text{O}}\text{C + C}\widehat{\text{O}}A=A\widehat{\text{O}}B\] and.

\[A\widehat{\text{O}}B=2\text{B}\widehat{\text{O}}\text{C}=2\text{C}\widehat{\text{O}}A\]


Parallel Lines

  • Even if they are extended on each side, two lines are parallel if they are coplanar and do not overlap.

  • There are, however, lines that don't intersect yet aren't parallel. 

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  • They're skew lines, as the name implies. Lines that are not coplanar and do not intersect are referred to as skew lines. 

  • The lines \[\text{AE}\] and \[\text{HG}\] are skewed.

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Transversal

  • Observe the three lines '\[\text{l}\]', '\[\text{m}\]' and '\[\text{t}\]'.

  • In the diagram '\[\text{l}\]' and '\[\text{m}\]' are two parallel lines. '\[\text{t}\]' intersects '\[\text{l}\]' at two distinct points '\[\text{A}\]' and '\[\text{B}\]' and '\[\text{m}\]' at '\[\text{C}\]' and '\[\text{D}\]'. Line t is known as transversal.

  • A transversal is a line that at different points intersects (or slices) two or more parallel lines.

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Angles Formed by a Transversal 

  • In the diagram \[\overleftrightarrow{\text{AB}}\] and \[\overleftrightarrow{\text{CD}}\] are two parallel lines. 

\[\text{PQRS}\] is a transversal intersecting \[\overleftrightarrow{\text{AB}}\] at \[Q\] and \[\overleftrightarrow{\text{CD}}\] at \[\text{R}\]. 

There are total eight angles formed.

  • Some of the angles can be grouped together due to their placements. Special names are given to the paired angles (apart from adjacent angles and vertical angles).

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Interior Angles which are on the same side of the Transversal

  • From the below figure,

\[A\widehat{Q}\text{R }\left( \angle 4 \right)\] and \[Q\widehat{R}\text{C }\left( \angle 5 \right)\] and \[B\widehat{Q}\text{R }\left( \angle 3 \right)\] and \[Q\widehat{R}\text{D }\left( \angle 6 \right)\] form two pairs of interior angles on the same side of the transversal.

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Alternate Angles

  • A pair of angles are said to be alternate angles if

  1. both angles are internal angles,

  2. they're on opposing sides of the transversal axis, and

  3. they are not adjacent angles, they are said to be alternate angles.

  • Alternate interior angles are another name for alternate angles.

(Image will be Uploaded Soon)

  • In the above figure,

\[A\widehat{Q}\text{R}\]and \[Q\widehat{R}\text{D}\] \[\left( \angle \text{4 and }\angle 6 \right)\]

\[B\widehat{Q}\text{R}\] and \[Q\widehat{R}\text{C}\] \[\left( \angle \text{3 and }\angle 5 \right)\] are the two pairs of alternate angles.


Corresponding Angles 

  • A pair of angles are said to be corresponding angles if 

  • One is an interior angle and the other is an exterior angle 

  • They are in the same transverse plane and 

  • They are not adjacent angles. 

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The four pairs of corresponding angles are given as follows;

\[A\widehat{Q}\text{P}\]and \[C\widehat{R}\text{Q}\] \[\left( \angle \text{1 and }\angle 5 \right)\]

\[A\widehat{Q}\text{R}\] and \[C\widehat{R}\text{E}\] \[\left( \angle \text{4 and }\angle 8 \right)\]

\[B\widehat{Q}\text{R}\] and \[D\widehat{R}\text{E}\] \[\left( \angle \text{3 and }\angle 7 \right)\]


Parallel Lines - Theorem 1

  • Statement: 

Each pair of alternating angles is equal when a transversal intersects two parallel lines.

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  • Given: 

$\Delta \text{ABC}$, side $\text{BC}$ is produced to $D$ and \[\text{A}\widehat{\text{C}}\text{D}\]is the exterior angle formed.

\[\text{AB  }\!\!|\!\!\text{  }\!\!|\!\!\text{  CD}\] and \[\text{EFGH}\] is a transversal.


  • To Prove: 

\[\text{A}\widehat{F}D=F\widehat{G}D\] (One pair of interior alternate angles)

\[B\widehat{F}G=F\widehat{G}C\] (Another pair of interior alternate angles)


  • Proof:

\[\text{A}\widehat{F}G=E\widehat{F}B\] (Vertically opposite angles)

But

\[E\widehat{F}B=F\widehat{G}D\] (Corresponding angles)

\[\therefore \text{A}\widehat{F}G=F\widehat{G}D\]

Now,

\[B\widehat{F}G+\text{A}\widehat{F}G={{180}^{\circ }}.....\left( \text{i} \right)\left( \text{Linear Pair} \right)\]

\[F\widehat{G}C+F\widehat{G}D={{180}^{\circ }}.....\left( \text{ii} \right)\left( \text{Linear Pair} \right)\]

From \[\left( \text{i} \right)\] and \[\left( \text{ii} \right)\],

\[B\widehat{F}G+\text{A}\widehat{F}G=F\widehat{G}C+F\widehat{G}D\]

But

\[\text{A}\widehat{F}G=F\widehat{G}\text{D}\left( \text{Proved} \right)\]

\[\therefore B\widehat{F}G=F\widehat{G}C\]


Converse of Theorem $1$

  • Statement: 

If a transversal intersects two lines in such a way that a pair of alternate interior angles are equal, then the two lines are parallel.

(Image will be Uploaded Soon)


  • Given: 

Transversal \[\text{EFGH}\] intersects lines \[\text{AB}\] and \[\text{CD}\] such that a pair of alternate angles are equal.

\[\left( \text{A}\widehat{F}D=F\widehat{G}D \right)\]


  • To Prove: 

\[\text{AB  }\!\!|\!\!\text{  }\!\!|\!\!\text{  CD}\]


  • Proof:

\[\text{A}\widehat{F}G=F\widehat{G}D\] (Given)

But

\[A\widehat{F}G=E\widehat{F}B\]  (Vertically opposite angles)

\[\therefore E\widehat{F}B=F\widehat{G}D\] (Corresponding angles)

Therefore,

\[\text{AB  }\!\!|\!\!\text{  }\!\!|\!\!\text{  CD}\] (Corresponding angles axiom)


Parallel Lines - Theorem $2$

  • Statement: 

Each set of consecutive interior angles is additional or supplementary when a transversal connects two parallel lines.

(Image will be Uploaded Soon)


  • Given: 

\[\text{AB  }\!\!|\!\!\text{  }\!\!|\!\!\text{  CD}\] and \[\text{EFGH}\] is a transversal.


  • To Prove: 

\[B\widehat{F}G+F\widehat{G}D={{180}^{\circ }}\]

\[A\widehat{F}G+F\widehat{G}C={{180}^{\circ }}\]


  • Proof:

\[E\widehat{F}B+B\widehat{F}G={{180}^{\circ }}\] (Linear Pair)

But

\[E\widehat{F}B=F\widehat{G}D\] (Corresponding angles axiom)

\[\therefore B\widehat{F}G+F\widehat{G}D={{180}^{\circ }}\] (Substitute \[F\widehat{G}D\] for \[E\widehat{F}B\])

Similarly, we can prove that

\[A\widehat{F}G+F\widehat{G}C={{180}^{\circ }}\]


Converse of Theorem $2$

  • Statement: 

If a transversal intersects two lines in such a way that a pair of consecutive interior angles are supplementary, then the two lines are parallel.

(Image will be Uploaded Soon)


  • Given: 

Transversal \[\text{EFGH}\] intersects lines \[\text{AB}\] and \[\text{CD}\] at \[\text{F}\] and \[\text{G}\] such that \[B\widehat{F}G\] and \[F\widehat{G}D\] are supplementary.

That is \[\left( B\widehat{F}G+F\widehat{G}D={{180}^{\circ }} \right)\]


  • To Prove: 

\[\text{AB  }\!\!|\!\!\text{  }\!\!|\!\!\text{  CD}\]


  • Proof:

\[E\widehat{F}B+B\widehat{F}G={{180}^{\circ }}......\left( \text{i} \right)\] (Linear pair (ray \[\text{FB}\] stands on \[\text{EFGH}\]))

(Corresponding angles postulate)

\[B\widehat{F}G+F\widehat{G}D={{180}^{\circ }}.....\left( \text{ii} \right)\] (Given)

\[E\widehat{F}B+B\widehat{F}G=B\widehat{F}G+F\widehat{G}D\]

Therefore,

\[E\widehat{F}B=F\widehat{G}D\] (Subtract \[B\widehat{F}G\] from both sides)

Since these are corresponding angles,

Therefore,

\[\text{AB  }\!\!|\!\!\text{  }\!\!|\!\!\text{  CD}\] 


Interior and Exterior Angles of a Triangle

  • When we talk about an angle in a triangle, we're talking about the angle formed by the two sides. 

  • The three angles are located in the triangle's interior. These angles are known as the triangle's inner angles. 

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  • Now look at the triangle that the sides are formed in.

  • In the fig, is extended to $\text{O}$. An angle $\text{OXZ}$ is formed.

$\overline{\text{XZ}}$ is produced to $\text{P}$ forming an angle $\text{YZP}$. 

  • Similarly, $\overline{\text{ZY}}$ is formed to $\text{M}$ forming angle $\text{MYX}$. 

  • These angles $\text{OXZ, YZP}$and $\text{MYX}$X are called exterior angles of $\text{ABC}$ 

  • There can be three external angles because the triangle has three sides. 

  • The interior angles opposite to the vertices where the exterior angles are formed, are called the interior opposite angles. 

  • From the figure, at $\text{X}$, the exterior angle $\text{OXZ}$ is formed and angles $\text{XYZ}$ and $\text{XZY}$are interior opposite angles of it.

(Image will be Uploaded Soon)

From above figure,

For exterior angle $1$; the interior opposite angles are \[\text{B}\widehat{A}C\] and \[\text{A}\widehat{B}C\].

For exterior angle $2$; the interior opposite angles are \[\text{A}\widehat{B}C\] and \[\text{A}\widehat{C}B\].

For exterior angle $3$; the interior opposite angles are \[\text{B}\widehat{A}C\] and \[\text{A}\widehat{C}B\].


Triangles - Theorem $1$:

  • Statement: 

If a side of a triangle is produced, the exterior angle so formed is equal to the sum of the interior opposite angles.

(Image will be Uploaded Soon)


  • Given: 

In triangle, $\Delta \text{ABC}$, side $\text{BC}$ is produced to $D$ and \[\text{A}\widehat{\text{C}}\text{D}\]is the exterior angle formed.

\[\text{A}\widehat{B}C\] and \[B\widehat{A}C\] are the interior opposite angles.


  • To Prove: 

\[\text{A}\widehat{C}D=\text{A}\widehat{B}C+\text{B}\widehat{A}C\]


  • Proof:

\[A\widehat{B}C+B\widehat{A}C+A\widehat{C}B={{180}^{\circ }}......\left( \text{i} \right)\] (Theorem) 

\[A\widehat{C}B+A\widehat{C}D={{180}^{\circ }}......\left( \text{ii} \right)\] (Linear pair) 

From \[\left( \text{i} \right)\] and \[\left( \text{ii} \right)\], we get

\[\text{A}\widehat{B}C+\text{B}\widehat{A}C+\text{A}\widehat{C}B=\text{A}\widehat{C}B+\text{A}\widehat{C}D\]

Subtract \[\text{A}\widehat{C}B\] from both sides, we get

\[\text{A}\widehat{B}C+\text{B}\widehat{A}C=\text{A}\widehat{C}D\]


Angle Sum Property

Three line segments unite three non-collinear points to make a triangle, which is a plane closed geometric figure.


Triangles - Theorem $2$:

  • Statement: 

The sum of the three angles of a triangle is ${{180}^{\circ }}$.

(Image will be Uploaded Soon)


  • Given: 

A triangle $\text{MNS}$. 


  • To Prove: 

$\widehat{M}+\widehat{N}+\widehat{S}={{180}^{\circ }}$


  • Construction:

By using a scale through the vertex $\text{M}$, draw a line $\overleftrightarrow{AB}$ parallel to the base $\overline{NS}$.


  • Proof:

$\overline{NS}||\overleftrightarrow{AB}$

$\text{MN}$ is a transversal.

Therefore,

$\text{A}\widehat{\text{M}}\text{N = M}\widehat{\text{N}}\text{S }.....\left( 1 \right)\text{ Alternate angles}$

Similarly, \[\overleftrightarrow{AB}||\overline{NS}\] and \[MN\]

Therefore,

$\text{B}\widehat{\text{M}}\text{S = M}\widehat{\text{S}}\text{N }.....\left( 2 \right)\text{ Alternate angles}$

From the figure,

$\text{A}\widehat{\text{M}}\text{N + N}\widehat{M}\text{S + B}\widehat{M}S={{180}^{\circ }}$

Since, \[\overleftrightarrow{AB}\] is a straight line and sum of the angles at $M={{180}^{\circ }}$

From $\left( 1 \right)$and $\left( 2 \right)$,

$M\widehat{N}\text{S + N}\widehat{M}\text{S + M}\widehat{S}N={{180}^{\circ }}$ - By substituting $M\widehat{N}\text{S}$ and $\text{M}\widehat{S}N$

Thus it is proved that sum of the measures of the three angles of a triangle is equal to ${{180}^{\circ }}$ or two right angles.


Lines and Angles Class 9 Notes NCERT

Lines and Angles Notes Class 9 PDF

All the notes of Chapter 6 Maths Class 9 are available to download in PDF format. Students get the flexibility to study at their comfort and pace. They also do not need any internet connection to refer to these Class 9 Chapter 6 Maths notes. An internet connection would only be needed the first time to download the notes. The students can neatly arrange these Class 9th Maths Chapter 6 notes in a folder on their laptop or their smartphone and refer to them when in any doubt. Before the exam preparation or before any competitive examination, students can refer to these notes and get all their doubts solved. The notes of Lines and Angles Class 9 are detailed, and thus students can brush through the notes before the exam.


NCERT Class 9 Maths Chapter 6 Notes Revision

Our revision Class 9 Maths Ch 6 notes cover the topic in great detail. Here are the notes for this chapter.

  • A point is a dot that does not have any component.

  • A line is formed when two different points are joined. There are no endpoints in the line, and this can be extended till infinity.

  • A line segment is a line that has two endpoints.

  • A ray is a line that has an endpoint at one end, but the other end stretches to infinity.

  • Points that are on the same line are collinear. Points that do not lie on the same line are non-collinear


Angles

An angle is made when two rays start from the same endpoint. The two rays form arms of the angle. The endpoints are the vertex of the angle. 


The Types of Angles

  • An angle that is between 0 and 90 degrees is acute.

  • An angle that is exactly equal to 90 degrees is a right angle

  • An angle that lies between 90 and 180 degrees is obtuse.

  • A reflex angle lies between 180 and 360 degree

  • If the angle is exactly equal to 180 degrees, then this is a straight angle

  • A complete angle is the one that is equal to precisely 360 degree


Complementary and Supplementary Angles

  • If the sum of the angles is equal to 90 degrees then these are complementary angles

  • If the sum of the angles is equal to 180 degrees, then this is supplementary angles

  • Adjacent angles are angles that have a similar vertex, and one of their arms is common.

  • Linear pairs of angles have two angles with the same vertex and have one common arm. The arms that are not common make a line.

  • Where two lines intersect each other at one point, then the opposite angle is called the vertically opposite angle.


Intersecting and Non-Intersecting Lines

Intersecting lines are those lines that cross each other from one particular point. Non- intersecting lines are those that never cross each other at one point. These are parallel lines, and the common distance between the lines stays the same.


The Pairs of Angles Axioms

If the rays stand on one line, then the sum of its two adjacent angles formed by the ray is 180 degrees.

If the sum of the two adjacent angles is 180 degrees, then the arm that is not common to the angle forms a line.


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  1. CBSE Class 9 Maths notes for Chapter 6 provide an overview of the chapter to the students in a concise form.

  2. Students can revise all important formulas and topics of the chapter quickly.

  3. Studying through the notes will save students time.

  4. Students will be able to recall all the important concepts of the chapter just by having a look at the notes.

  5. It helps students to quickly revise all the important concepts of the chapter just before the exam days.


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FAQs on Lines and Angles Class 9 Notes CBSE Maths Chapter 6 (Free PDF Download)

1. What is the thorium of vertically opposite angles?

When two lines intersect each other, then the vertically opposite angles that get formed are equal.

2. What is a transversal line?

If there is a line that passes through two lines that are distinct and the line intersects the lines at distance points, then the line is a transversal line.

3. What is the difference between a line and a line segment?

A line segment is a line that joins two points, but it ends till infinity on both sides.

A line segment has two endpoints. Thus the line segment has a definite start and end and does not go indefinitely.

4. What do collinear and non-collinear points mean?

If two points fall on the same line, then these are collinear points. If there are points that do not lie on the same line, then these are non-collinear points.

5. Which are the lines that do not meet?

Parallel lines are lines that will never meet each other if extended from both sides till infinity. The distance between two parallel lines stays the same throughout.

6. How can I use these notes effectively for my studies?

To make the best use of these notes, read through them carefully, take notes if needed, and attempt the practice problems or exercises if provided. These notes can be a valuable supplement to your regular textbook and class notes.

7.  Do these notes cover all the topics in Chapter 6 of the CBSE Maths textbook?

Generally, yes. These notes should cover all the important topics and concepts found in Chapter 6, including definitions, properties of angles and lines, theorems, and practical applications.