CBSE Class 8 Mathematics Lines and Angles MCQs Set 19

Mathematics Objective Questions and Answers: Lines and Angles

Access targeted multiple-choice questions for Lines and Angles designed to align with the latest CBSE academic syllabus for Class 8 Mathematics. These objective practice sets help students evaluate their conceptual understanding and improve exam readiness.

Download Lines and Angles MCQs with Answers

View or download the dedicated Lines and Angles MCQ resource below. Practicing these 50 objective questions regularly builds familiarity with standard exam patterns and helps secure higher marks in final Mathematics evaluations.

Multiple Choice Questions

Question 1: Angles of measures 50° and ___ are complementary.
(a) 50°
(b) 40°
(c) 130°
(d) 90°
Show Answer & Explanation

Answer: (b) 40°

Explanation:
1. Complementary angles add to 90°: 90° − 50° = 40°.

Teacher's Note:
1. Complementary = sum 90°.
2. Supplementary = sum 180°.

Question 2: Two angles whose sum is 180° are called
(a) adjacent angles
(b) supplementary angles
(c) complementary angles
(d) vertically opposite angles
Show Answer & Explanation

Answer: (b) supplementary angles

Explanation:
1. By definition, two angles with sum 180° are supplementary.

Teacher's Note:
1. Supplementary pairs on a straight line are linear pairs.
2. Complementary pairs sum to 90°.

Question 3: Angles of measure 115° and ___ form a pair of supplementary angles.
(a) 55°
(b) 65°
(c) 75°
(d) 25°
Show Answer & Explanation

Answer: (b) 65°

Explanation:
1. 180° − 115° = 65°.

Teacher's Note:
1. Subtract from 180°.
2. Check: 115° + 65° = 180°.

Question 4: If two angles of a triangle are complementary, the triangle is
(a) an isosceles triangle
(b) an equilateral triangle
(c) a right triangle
(d) an obtuse triangle
Show Answer & Explanation

Answer: (c) a right triangle

Explanation:
1. The two angles add to 90°, so the third angle is 180° − 90° = 90°.
2. Hence the triangle is right-angled.

Teacher's Note:
1. Use the angle sum property of a triangle.
2. The third angle is 90°.

Question 5: The exterior angle of a triangle is 72° and its two opposite interior angles are equal. Each of these angles is
(a) 54°
(b) 18°
(c) 72°
(d) 36°
Show Answer & Explanation

Answer: (d) 36°

Explanation:
1. Exterior angle = sum of the two opposite interior angles: 72° = 2x.
2. x = 36°.

Teacher's Note:
1. Exterior angle property.
2. Each equal angle is half of 72°.

Question 6: The angles of a triangle are in the ratio 4 : 5 : 9. The largest angle is
(a) 72°
(b) 100°
(c) 90°
(d) 80°
Show Answer & Explanation

Answer: (c) 90°

Explanation:
1. 4 + 5 + 9 = 18, so one part = 180° / 18 = 10°.
2. Angles are 40°, 50°, 90°; the triangle is right-angled.

Teacher's Note:
1. Divide 180° in the ratio.
2. Largest = 9 × 10° = 90°.

Question 7: In a right triangle, the angle between the bisectors of the two acute angles is
(a) 90°
(b) 120°
(c) 45°
(d) 135°
Show Answer & Explanation

Answer: (d) 135°

Explanation:
1. The acute angles add to 90°, so their halves add to 45°.
2. The angle at the intersection = 180° − 45° = 135°.

Teacher's Note:
1. Use the angle sum in the small triangle.
2. Half of 90° is 45°.

Question 8: The bisectors of the base angles of a triangle enclose an angle of 135°. The triangle is
(a) obtuse-angled
(b) isosceles but not right-angled
(c) equilateral
(d) right-angled
Show Answer & Explanation

Answer: (d) right-angled

Explanation:
1. Half-angles sum = 180° − 135° = 45°, so the base angles sum to 90°.
2. The third angle is 90°, so the triangle is right-angled.

Teacher's Note:
1. Work backwards from 135°.
2. Base angles sum to 90°.

Question 9: The measure of an angle which is four times its complement is
(a) 60°
(b) 80°
(c) 72°
(d) 36°
Show Answer & Explanation

Answer: (c) 72°

Explanation:
1. x = 4(90° − x), so 5x = 360° and x = 72°.
2. Check: complement is 18° and 4 × 18° = 72°.

Teacher's Note:
1. Complement = 90° − x.
2. Form an equation.

Question 10: The measure of an angle which is 32° less than its supplement is
(a) 74°
(b) 106°
(c) 58°
(d) 64°
Show Answer & Explanation

Answer: (a) 74°

Explanation:
1. x = (180° − x) − 32°, so 2x = 148° and x = 74°.
2. Check: supplement 106° and 106° − 74° = 32°.

Teacher's Note:
1. Supplement = 180° − x.
2. Solve the linear equation.

Question 11: If an angle is 28° less than its complement, then its measure is
(a) 59°
(b) 62°
(c) 31°
(d) 28°
Show Answer & Explanation

Answer: (c) 31°

Explanation:
1. x = (90° − x) − 28°, so 2x = 62° and x = 31°.
2. Complement is 59° and 59° − 31° = 28°.

Teacher's Note:
1. Complement = 90° − x.
2. Check by subtraction.

Question 12: The measure of an angle is twice the measure of its supplementary angle. The angle is
(a) 120°
(b) 135°
(c) 60°
(d) 90°
Show Answer & Explanation

Answer: (a) 120°

Explanation:
1. x = 2(180° − x), so 3x = 360° and x = 120°.
2. Its supplement is 60°.

Teacher's Note:
1. Supplement = 180° − x.
2. 120° is twice 60°.

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Practice MCQs for Class 8 Mathematics Lines and Angles

Download Multiple Choice Questions: Lines and Angles (Class 8 Mathematics)

Explore reliable practice questions for Lines and Angles tailored for Class 8 Mathematics learners. Use these multiple-choice formats to evaluate preparedness and strengthen problem-solving skills.

Concept Clarification for Lines and Angles

Each question includes structured solution keys mapped directly to standard CBSE textbooks, helping students evaluate their reasoning and correct mistakes early in their revision.

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FAQs

Where can I access latest CBSE Class 8 Mathematics Lines and Angles MCQs Set 19?

You can get most exhaustive CBSE Class 8 Mathematics Lines and Angles MCQs Set 19 for free on StudiesToday.com. These MCQs for Class 8 Mathematics are updated for the 2026-27 academic session as per CBSE examination standards.

Are Assertion-Reasoning and Case-Study MCQs included in the Mathematics Class 8 material?

Yes, our CBSE Class 8 Mathematics Lines and Angles MCQs Set 19 include the latest type of questions, such as Assertion-Reasoning and Case-based MCQs. 50% of the CBSE paper is now competency-based.

How do practicing Mathematics MCQs help in scoring full marks in Class 8 exams?

By solving our CBSE Class 8 Mathematics Lines and Angles MCQs Set 19, Class 8 students can improve their accuracy and speed which is important as objective questions provide a chance to secure 100% marks in the Mathematics.

Do you provide answers and explanations for CBSE Class 8 Mathematics Lines and Angles MCQs Set 19?

Yes, Mathematics MCQs for Class 8 have answer key and brief explanations to help students understand logic behind the correct option as its important for 2026 competency-focused CBSE exams.

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Yes, you can also access online interactive tests for CBSE Class 8 Mathematics Lines and Angles MCQs Set 19 on StudiesToday.com as they provide instant answers and score to help you track your progress in Mathematics.