NCERT Solutions for Class 9 Maths Chapter 6 : Lines and Angles

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The NCERT Solutions for Class 9 Maths have been provided in this article. Lines are dots spaced together that extend infnitely in two directions. Angles are shapes that form once two rays meet at the endpoint.

Class 9 Maths Chapter 6 Lines and Angles belong to Unit 4 Geometry which has a weightage of 27 marks in the Class 9 Maths Examination. NCERT Solutions for Class 9 Maths for Chapter 6 cover the following important concepts: 

  • Angle Sum Property of a Triangle
  • Lines and Angles
  • Parallel Lines and a Transversal

Download: NCERT Solutions for Class 9 Mathematics Chapter 6 pdf


NCERT Solutions for Class 9 Mathematics Chapter 6

The Chapter 6 Class 9 Maths are given below:

NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics NCERT Solutions Mathematics

Important Topics in Class 9 Maths Chapter 6 Lines and Angles

Important Topics in Class 9 Maths Chapter 6 Lines and Angles are elaborated below:

Angle Sum Property of a Triangle

Angle sum property of a triangle claims that the sum of interior angles of a triangle is 180°. It is used to determine the measure of an unknown interior angle when the values of the other  angles are known.

Angle Sum Property of a Triangle can be expressed by the following formula:
S = ( n − 2) × 180°

Lines and Angles

A line is a straight one-dimensional shape that extends infinitely in two directions. Angles form when two lines intersect one another. It can be represented by the symbol ∠.

Example: List what happens when two parallel lines are intersected by a transversal?

Solution: Assuming that two parallel lines are intersected by a transversal, the following occurs:

  • The vertically opposite angles are equal.
  • The corresponding angles are equal as well.
  • The alternate exterior and interior angles are equal too.

Parallel Lines and a Transversal

Parallel lines always remain the same distance apart and actually never meet. While, a transversal is any line that intersects two or more lines.

Example: What are some properties of a Transversal?

Solution: Some properties of a transversal are:

  • Its corresponding angles are always equal.
  • Its vertically opposite angles are found equal.
  • Its alternate interior angles are equal too.
  • Its alternate exterior angles are equal too.

NCERT Solutions for Class 9 Maths Chapter 6 Exercises:

The detailed solutions for all the NCERT Solutions for Lines and Angles under different exercises are:

Also check:

Also Read:

CBSE X Related Questions

  • 1.

    In the adjoining figure, $\triangle CAB$ is a right triangle, right angled at A and $AD \perp BC$. Prove that $\triangle ADB \sim \triangle CDA$. Further, if $BC = 10$ cm and $CD = 2$ cm, find the length of AD.


      • 2.
        The number of red balls in a bag is three more than the number of black balls. If the probability of drawing a red ball at random from the given bag is $\dfrac{12}{23}$, find the total number of balls in the given bag.


          • 3.

            Given that $\sin \theta + \cos \theta = x$, prove that $\sin^4 \theta + \cos^4 \theta = \dfrac{2 - (x^2 - 1)^2}{2}$.


              • 4.

                Find the mean and mode of the following data:

                Class15--2020--2525--3030--3535--4040--45
                Frequency1210151175


                  • 5.

                    On the day of her examination, Riya sharpened her pencil from both ends as shown below.

                    The diameter of the cylindrical and conical part of the pencil is 4.2 mm. If the height of each conical part is 2.8 mm and the length of the entire pencil is 105.6 mm, find the total surface area of the pencil.


                      • 6.
                        Let $p$, $q$ and $r$ be three distinct prime numbers. Check whether $pqr + q$ is a composite number or not. Further, give an example for three distinct primes $p$, $q$, $r$ such that
                        (i) $pqr + 1$ is a composite number
                        (ii) $pqr + 1$ is a prime number

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