Read and download the CBSE Class 9 Mathematics Lines And Angles Worksheet Set 01 in PDF format. We have provided exhaustive and printable Class 9 Mathematics worksheets for Chapter 6 Lines and Angles, designed by expert teachers. These resources align with the 2026-27 syllabus and examination patterns issued by NCERT, CBSE, and KVS, helping students master all important chapter topics.
Practice Worksheet: Class 9 Mathematics Chapter 6 Lines and Angles
Every student in Class 9 can use this Mathematics practice paper to review Chapter 6 Lines and Angles. Complete with important questions and solutions, regular self-testing will boost your confidence and improve your grades in school assessments and final tests.
Get Chapter 6 Lines and Angles Worksheet PDF for Class 9 Mathematics
CBSE Class 9 Mathematics Worksheet Lines and Angles - Practice worksheets for CBSE students. Prepared by teachers of the best CBSE schools in India.
ASSERTION & REASONING QUESTIONS
DIRECTION : In the following questions, a statement of assertion (A) is followed by a statement of reason (R).
Mark the correct choice as:
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A) .
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A) .
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.
Question. Assertion : If angles ‘a ’ and ‘b’ form a linear pair of angles and a = 40°, then b = 150°.
Reason : Sum of linear pair of angles is always 180°.
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A) .
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A) .
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.
Answer : We know that the sum of linear pair of angles is always 180°.
So, Reason is correct.
Now, a + b = 40° + 150° = 190° ≠180°
Hence, Assertion is not correct
Correct option is (d) Assertion (A) is false but reason (R) is true.
Question. Assertion : If two interior angles on the same side of a transversal intersecting two parallel lines are in the ratio 5 : 4, then the greater of the two angles is 100°.
Reason : If a transversal intersects two parallel lines, then the sum of the interior angles on the same side of the transversal is 180°.
Answer : We know If a transversal intersects two parallel lines, then the sum of the interior angles on the same side of the transversal is 180° hat the solution of the line will satisfy the equation of the line.
So, Reason is correct.
Let the angles be 5x and 4x
Since, these two angles are co-interior angles. So, we
have 5x + 4x = 180° ⇒ 9x = 180° ⇒ x = 20°
Hence, greater angle = 5x = 5 x 20° = 100°
So, Assertion is also correct
Correct option is (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A) .
Question. Assertion : An angle is 140 more than its complementary angle, then angle is 520.
Reason : Two angles are said to be supplementary if their sum of measure of angles is 180°.
Answer : We know that two angles are said to be supplementary if their sum of measure of angles is 180°.
So, Reason is correct.
Let the angle be x . Complement of x = (90° - x)
Since, the difference is 140, we have x – (90° – x) = 140
⇒ 2x = 104°
⇒ x = 52°
So, Assertion is also correct
But reason (R) is not the correct explanation of assertion (A) .
Correct option is (b) Both assertion (A) and reason (R) are true and reason (R) is not the correct explanation of assertion (A) .
Question. Assertion : Supplement of angle is one fourth of itself. The measure of the angle is 1440.
Reason : Two angles are said to be supplementary if their sum of measure of angles is 180°.
Answer : We know that two angles are said to be supplementary if their sum of measure of angles is 180°.
So, Reason is correct.
Let the angle be x . Supplement of x = (1/4) x
So, x + 1/2 x = 180° ⇒ (5/4) x = 180° ⇒ x = 144°
So, Assertion is also correct
Also, reason (R) is the correct explanation of assertion (A) .
Correct option is (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A) .
Question. Assertion: The value of x from the adjoining figure, if l || m is 150.
Reason: If two parallel lines are intersected by a transversal, then each pair of corresponding angles so formed is equal.
Answer : We know that If two parallel lines are intersected by a transversal, then each pair of corresponding angles so formed is equal.
So, Reason is correct.
Also, we know that If a transversal intersects two parallel lines, then the sum of the interior angles on the same side of the transversal is 180°.
From figure we have, 120° – x + 5x = 180°
⇒ 4x = 180° – 120°
⇒ 4x = 60°
⇒ x = 15°
So, Assertion is also correct.
But reason (R) is not the correct explanation of assertion (A) .
Correct option is (b) Both assertion (A) and reason (R) are true and reason (R) is not the correct explanation of assertion (A) .
Question. Assertion : If two internal opposite angles of a triangle are equal and external angle is given to be 110°, then each of the equal internal angle is 55°.
Reason : A triangle with one of its angle 900, is called a right triangle.
Answer : For Assertion: We know that the exterior angle is equal to the sum of its interior opposite angles. So, x + x = 110°.
⇒ 2x = 110°
⇒ x = 55°
So, Assertion is correct
Also, we know that a triangle with one of its angle 900, is called a right triangle.
So, Reason is also correct.
But reason (R) is not the correct explanation of assertion (A) .
Correct option is (b) Both assertion (A) and reason (R) are true and reason (R) is not the correct explanation of assertion (A) .
Question. Assertion : Sum of the pair of angles 120° and 60° is supplementary.
Reason : Two angles, the sum of whose measures is 180°, are called supplementary angles.
Answer : We know that two angles are said to be supplementary if their sum of measure of angles is 180°.
So, Reason is correct.
Now, 120° + 60° = 180° ⇒ Sum of the pair of angles 120° and 60° is supplementary.
So, Assertion is also correct
Also, reason (R) is the correct explanation of assertion (A) .
Correct option is (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A) .
Question. Assertion : A triangle can have two obtuse angles.
Reason : The sum of all the interior angles of a triangle is 180°
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A) .
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A) .
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.
Answer : We know that the sum of all the interior angles of a triangle is 180°.
So, Reason (R) is true.
Since the Sum of two obtuse angles will be more than 180°.
So, Assertion (A) is false.
Correct option is (d) Assertion (A) is false but reason (R) is true.
Question. Assertion: The angles of a triangle are in the ratio 2 : 3 : 4. The largest angle of the triangle is 800.
Reason: The sum of all the interior angles of a triangle is 180°
Answer : We know that the sum of all the interior angles of a triangle is 180°.
So, Reason (R) is true.
Let the angles of a triangle be 2x, 3x and 4x then we have
2x + 3x + 4x = 180°
⇒ 9x = 180°
⇒ x = 20°.
Hence, Largest angle = 4 x 20° = 80°.
So, Assertion (A) is also true.
Also, Reason (R) is a correct explanation of Assertion (A) .
Correct option is (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A) .
Question. Assertion: In the given figure, AOB is a straight line. If ∠AOC = (3x + 10) ° and ∠BOC (4x − 26) °, then ∠BOC = 860
Reason: The sum of angles that are formed on a straight line is equal to 180°.
Answer : We know that the sum of angles that are formed on a straight line is equal to 180°.
So, Reason is correct
We have : ∠AOC+∠BOC=180° [Since AOB is a straight line ]
⇒3x + 10 + 4x − 26 = 180°
⇒7x = 196°
⇒x = 28°
∴∠BOC = [4 × 28 − 26]°
⇒∠BOC=86°.
So, Assertion (A) is also true.
Correct option is (a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A) .
Question. Assertion : The angles of a triangle are in the ration 3 : 5 : 7. The triangle is acuteangled
Reason : The sum of angles that are formed on a straight line is equal to 180°.
Answer : We know that the sum of angles that are formed on a straight line is equal to 180°.
So, Reason is correct
Also, the sum of all the interior angles of a triangle is 180°
Let the angles measure (3x) °, (5x) ° and (7x) °.
Then,3x + 5x + 7x = 180° ⇒15x = 180° ⇒x = 12°
Therefore, the angles are 3(12) °=36°, 5(12) °= 60° and 7(12) ° = 84°.
Hence, the triangle is acute-angled.
So, Assertion (A) is also true.
But reason (R) is not the correct explanation of assertion (A) .
Correct option is (b) Both assertion (A) and reason (R) are true and reason (R) is not the correct explanation of assertion (A) .
Students must free download and practice these worksheets to gain more marks in exams. CBSE Class 9 Mathematics Worksheet Lines and Angles
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Practice Questions & Worksheets for Class 9 Mathematics Chapter 6 Lines and Angles
Practice Exercises for Class 9 Mathematics
Prepare effectively for your upcoming evaluations by utilizing the curated practice tasks for Chapter 6 Lines and Angles featured above. Built by expert educators to reflect the current 2026 CBSE guidelines for Class 9, these tools support steady academic growth. Regular practice is strongly recommended for Class 9 students seeking lasting proficiency in Mathematics.
Detailed Answers & NCERT Integration
Crafted in direct consultation with the newest NCERT book for Class 9 Mathematics, these exercises provide authentic practice. Cross-checking your responses against our teacher-crafted detailed solutions teaches you proper presentation techniques required for CBSE exams. Additionally, reviewing the preceding MCQ questions for Mathematics ensures comprehensive coverage of every critical sub-topic within the chapter.
Boosting Grades with Free Mathematics Resources
Regular practice of this Class 9 Mathematics study material helps you to be familiar with the most regularly asked exam topics. If you find any topic in Chapter 6 Lines and Angles difficult then you can refer to our NCERT solutions for Class 9 Mathematics. All revision sheets and printable assignments on studiestoday.com are free and updated to help students get better scores in their school examinations.
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