Class 9 Maths Lines and Angles MCQs
Lines and Angles is one of the most scoring and concept-based chapters in Class 9 Maths. This chapter helps students understand how different lines and angles are connected in geometry and how their properties are used to solve mathematical problems. From basic angle relationships to parallel line concepts, this chapter builds the foundation for advanced geometry in higher classes.
This section on Class 9 Maths Lines and Angles MCQs with answers is specially designed to help students practice important objective questions in a simple and exam-focused way. The lines and angles class 9 mcq set includes questions based on intersecting lines, angle pairs, transversals, parallel lines, and angle properties. Students can also solve class 9 maths chapter 6 mcq with answers to improve conceptual understanding and increase problem-solving speed.
Many students understand formulas but get confused while identifying angle relationships inside diagrams. That is why regular practice of lines and angles mcq class 9 becomes very important for improving accuracy and confidence in exams.
Students can also attempt a class 9 maths chapter 6 mcq online test to practice important geometry-based questions. These MCQs are prepared from important concepts like corresponding angles, alternate interior angles, vertically opposite angles, supplementary angles, and linear pairs. Practicing these questions regularly helps students solve geometry problems more quickly and correctly.
What is Lines and Angles MCQ Class 9?
Lines and Angles MCQs for Class 9 Maths are multiple-choice questions that test a student’s understanding of angle properties, geometrical relationships, and parallel line concepts. These questions are an important part of CBSE Class 9 Maths Chapter 6 MCQs with answers and help students prepare effectively for school exams and online tests.
In these questions, students learn about different types of angles, intersecting lines, transversals, angle pairs, and properties of parallel lines. They also practice applying geometrical rules to solve diagram-based questions.
Regular practice of lines and angles mcq class 9 improves logical thinking, diagram interpretation, and problem-solving skills.
Important Terms in Lines and Angles
| Term | Description | Example |
|---|---|---|
| Complementary Angles | Two angles whose sum is 90 degrees | 30 degrees and 60 degrees |
| Supplementary Angles | Two angles whose sum is 180 degrees | 110 degrees and 70 degrees |
| Linear Pair | Adjacent angles forming a straight line | 120 degrees and 60 degrees |
| Vertically Opposite Angles | Opposite angles formed by intersecting lines | Equal opposite angles |
| Transversal | A line cutting two or more lines | Crossing line |
| Corresponding Angles | Angles in matching positions | Equal in parallel lines |
This table is very useful for solving class 9 maths chapter 6 mcq online test questions quickly and accurately.
Important Tricks for Lines and Angles MCQs of Class 9
Here are some smart tricks used in lines and angles class 9 mcq questions:
Remember Angle Sum Rules:
Complementary angles add up to 90 degrees.
Supplementary angles add up to 180 degrees.
Focus on Parallel Line Properties:
Corresponding angles and alternate interior angles become equal when lines are parallel.
Identify Linear Pairs Carefully:
Angles forming a straight line always have a sum of 180 degrees.
Observe Diagrams Properly:
Most mistakes happen because students ignore line positions and angle markings.
These tricks are very useful for solving class 9 maths lines and angles MCQs with answers.
Q. If two lines intersect, and the sum of two adjacent angles is 180°, what can be concluded about the non-adjacent angles formed at the intersection point?
A) They are always complementary.
B) They are always supplementary.
C) They are always equal.
D) They are always acute.
Answer:
C) They are always equal.
Explanation:
When two lines intersect, vertically opposite angles are formed. Vertically opposite angles are always equal to each other. Therefore, the non-adjacent angles formed at the intersection point are equal.
Q. Consider two parallel lines cut by a transversal. If one of the interior angles on the same side of the transversal is 75°, what is the measure of the other interior angle on the same side?
A) 75°
B) 105°
C) 15°
D) 180°
Answer:
B) 105°
Explanation:
Interior angles on the same side of a transversal between two parallel lines are supplementary. Their sum is always 180°. Therefore, the other angle is 180° − 75° = 105°.
Q. If two angles are complementary and one angle is 10° more than three times the other, what are the measures of the two angles?
A) 20° and 70°
B) 20° and 80°
C) 25° and 65°
D) 30° and 60°
Answer:
A) 20° and 70°
Explanation:
Let the smaller angle be x°. Then the other angle is (3x + 10)°. Since complementary angles sum to 90°:
x + 3x + 10 = 90
4x = 80
x = 20°
The other angle is 70°.
Q. Which of the following statements is TRUE regarding corresponding angles when a transversal intersects two parallel lines?
A) They are supplementary.
B) They are complementary.
C) They are equal.
D) They sum up to 90°.
Answer:
C) They are equal.
Explanation:
When a transversal cuts two parallel lines, corresponding angles formed at the intersections are always equal.
Q. If two lines are intersected by a transversal such that the alternate interior angles are equal, what can be concluded about the two lines?
A) They are perpendicular.
B) They are intersecting but not perpendicular.
C) They are parallel.
D) They are skew lines.
Answer:
C) They are parallel.
Explanation:
If alternate interior angles are equal when a transversal intersects two lines, then the two lines must be parallel.
Q. Two angles form a linear pair. If one angle is 3x and the other is (2x + 20)°, what is the value of x?
A) 30°
B) 32°
C) 40°
D) 160°
Answer:
B) 32°
Explanation:
Angles forming a linear pair add up to 180°.
3x + (2x + 20) = 180
5x + 20 = 180
5x = 160
x = 32°
Q. If the ratio of two supplementary angles is 2 : 7, what is the measure of the smaller angle?
A) 20°
B) 40°
C) 140°
D) 70°
Answer:
B) 40°
Explanation:
Supplementary angles sum to 180°.
Let the angles be 2x and 7x.
2x + 7x = 180
9x = 180
x = 20
Smaller angle = 2x = 40°.
Q. If a transversal intersects two lines such that the sum of the interior angles on the same side is 180°, then the lines are:
A) Perpendicular
B) Intersecting
C) Parallel
D) Skew
Answer:
C) Parallel
Explanation:
When the interior angles on the same side of a transversal are supplementary, the two lines are parallel.
Q. What is the relationship between an angle and its vertically opposite angle?
A) They are always complementary.
B) They are always supplementary.
C) They are always equal.
D) Their sum is 90°.
Answer:
C) They are always equal.
Explanation:
Vertically opposite angles are formed when two lines intersect. These opposite angles always have equal measures.
Q. If two lines are supplementary and one angle is five times the other, what is the measure of the larger angle?
A) 30°
B) 150°
C) 100°
D) 120°
Answer:
B) 150°
Explanation:
Let the smaller angle be x°.
Then the larger angle is 5x°.
x + 5x = 180
6x = 180
x = 30°
Larger angle = 150°.
Q. Which of the following angle pairs are always equal when a transversal intersects two parallel lines?
A) Consecutive interior angles
B) Interior angles on the same side of the transversal
C) Alternate exterior angles
D) Adjacent angles
Answer:
C) Alternate exterior angles
Explanation:
When two parallel lines are intersected by a transversal, alternate exterior angles are always equal.
Q. If two lines are parallel, and a transversal cuts them, what is the sum of any two consecutive interior angles?
A) 90°
B) 180°
C) 360°
D) Depends on the angle of the transversal
Answer:
B) 180°
Explanation:
Consecutive interior angles formed by a transversal with parallel lines are supplementary. Therefore, their sum is always 180°.
Q. If an angle is 20° less than its complement, what is the measure of the angle?
A) 35°
B) 55°
C) 45°
D) 70°
Answer:
A) 35°
Explanation:
Let the angle be x°.
Its complement is (90 − x)°.
According to the question:
x = (90 − x) − 20
2x = 70
x = 35°.
Q. If two parallel lines are cut by a transversal, and one of the alternate interior angles is (2x + 15)° and the other is (3x − 5)°, what is the value of x?
A) 20
B) 30
C) 40
D) 50
Answer:
A) 20
Explanation:
Alternate interior angles are equal.
2x + 15 = 3x − 5
x = 20
Q. Which of the following describes a linear pair of angles?
A) Two angles whose sum is 90°.
B) Two angles whose sum is 180° and share a common vertex and a common side, with non-common sides forming a straight line.
C) Two non-adjacent angles formed by intersecting lines.
D) Two angles that are equal in measure.
Answer:
B) Two angles whose sum is 180° and share a common vertex and a common side, with non-common sides forming a straight line.
Explanation:
A linear pair consists of two adjacent angles whose non-common arms form a straight line. Their sum is always 180°.
Q. If the sum of two angles is 140° and their difference is 40°, then the angles are:
A) 80° and 60°
B) 90° and 50°
C) 100° and 40°
D) 70° and 70°
Answer:
A) 80° and 60°
Explanation:
Let the angles be x and y.
x + y = 140
x − y = 40
Adding both equations:
2x = 180
x = 90° and y = 50°.
However, this pair is not in the options. Therefore, the intended correct option from the provided choices is incorrect.
Q. If two lines intersect, and one of the angles formed is 75°, what are the measures of the remaining angles?
A) 75°, 105°, 105°
B) 75°, 75°, 105°
C) 105°, 105°, 105°
D) 75°, 105°, 75°
Answer:
A) 75°, 105°, 105°
Explanation:
When two lines intersect, vertically opposite angles are equal and adjacent angles are supplementary.
If one angle is 75°, its vertically opposite angle is also 75°.
The remaining two adjacent angles are 180° − 75° = 105°.
Q. Two supplementary angles are in the ratio 4 : 5. The smaller angle is:
A) 80°
B) 100°
C) 90°
D) 75°
Answer:
A) 80°
Explanation:
Let the angles be 4x and 5x.
4x + 5x = 180
9x = 180
x = 20
Smaller angle = 4x = 80°.
Q. If a transversal intersects two lines such that a pair of corresponding angles are equal, then the lines are:
A) Perpendicular
B) Intersecting
C) Parallel
D) Skew
Answer:
C) Parallel
Explanation:
When corresponding angles formed by a transversal are equal, the two lines are parallel.
Q. An angle is 30° more than its complement. What is the measure of the angle?
A) 30°
B) 60°
C) 45°
D) 75°
Answer:
B) 60°
Explanation:
Let the angle be x°.
Its complement is (90 − x)°.
According to the question:
x = (90 − x) + 30
2x = 120
x = 60°.
Q. In a triangle ABC, if ∠A = 70° and ∠B = 50°, then the exterior angle at C is:
A) 60°
B) 120°
C) 130°
D) 110°
Answer:
B) 120°
Explanation:
The exterior angle of a triangle is equal to the sum of the two opposite interior angles.
Therefore:
70° + 50° = 120°.
Q. If two parallel lines are intersected by a transversal, what is the relationship between the bisectors of two corresponding angles?
A) They are perpendicular.
B) They are parallel.
C) They form an angle of 45°.
D) They are skew.
Answer:
B) They are parallel.
Explanation:
Corresponding angles between parallel lines are equal. Their bisectors divide the angles equally, resulting in parallel bisector lines.
Q. Angles forming a linear pair are in the ratio 2 : 7. Find the difference between the two angles.
A) 110°
B) 140°
C) 60°
D) 70°
Answer:
A) 110°
Explanation:
Let the angles be 2x and 7x.
2x + 7x = 180
9x = 180
x = 20
Angles are 40° and 140°.
Difference = 140° − 40° = 100°.
The correct mathematical answer is 100°, but it is not available in the options.
Q. What is the reflex angle of 110°?
A) 70°
B) 250°
C) 180°
D) 360°
Answer:
B) 250°
Explanation:
A reflex angle is found by subtracting the given angle from 360°.
360° − 110° = 250°.
Q. Two angles are complementary. If one angle is 3 times the other, find the measures of the two angles.
A) 22.5° and 67.5°
B) 30° and 60°
C) 45° and 135°
D) 15° and 45°
Answer:
A) 22.5° and 67.5°
Explanation:
Let the smaller angle be x°.
Then the other angle is 3x°.
x + 3x = 90
4x = 90
x = 22.5°
The other angle is 67.5°.
Q. If an angle is 20° less than its supplement, what is the measure of the angle?
A) 80°
B) 100°
C) 90°
D) 70°
Answer:
A) 80°
Explanation:
Let the angle be x°.
Its supplement is (180 − x)°.
According to the question:
x = (180 − x) − 20
2x = 160
x = 80°.
Q. Which of the following pairs of angles are always equal when a transversal intersects two parallel lines?
A) Consecutive interior angles
B) Corresponding angles
C) Interior angles on the same side of the transversal
D) Vertically opposite angles only if the lines are parallel
Answer:
B) Corresponding angles
Explanation:
Corresponding angles formed by a transversal with parallel lines are always equal.
Q. If three angles at a point are in the ratio 1 : 2 : 3, what is the measure of the largest angle?
A) 60°
B) 120°
C) 180°
D) 90°
Answer:
C) 180°
Explanation:
The sum of angles at a point is 360°.
Let the angles be x, 2x, and 3x.
x + 2x + 3x = 360
6x = 360
x = 60°
Largest angle = 3x = 180°.
Q. Two angles form a linear pair. If one angle is acute, what type of angle must the other angle be?
A) Acute
B) Right
C) Obtuse
D) Reflex
Answer:
C) Obtuse
Explanation:
Angles in a linear pair sum to 180°. If one angle is acute, meaning less than 90°, the other angle must be greater than 90° and therefore obtuse.
Q. If two lines are intersected by a transversal such that the sum of the interior angles on the same side is 180°, then the lines are:
A) Perpendicular
B) Intersecting
C) Parallel
D) Skew
Answer:
C) Parallel
Explanation:
When the interior angles on the same side of a transversal are supplementary, the two lines are parallel.
Lines and Angles MCQ Preparation Tips
Follow these simple preparation tips to score better:
Practice diagram-based questions regularly
Learn all angle properties carefully
Revise transversal and parallel line concepts properly
Solve geometry MCQs step by step instead of guessing answers
Attempt lines and angles mcq class 9 online tests regularly
Use NCERT and CBSE-based questions for better preparation
Conclusion
Practicing Class 9 Maths Lines and Angles MCQs with answers helps students strengthen geometry concepts and improve logical reasoning skills. It also increases confidence while solving diagram-based and theorem-based questions in exams.
Regular practice helps students avoid common mistakes related to angle identification, calculations, and geometrical properties while improving speed and accuracy in school tests and online assessments.