LINES AND ANGLES – ANSWER KEY
Class 6 | Chapter 2 | Total Questions: 52
📘 Topic-wise Answer Key with Explanations & Competencies
1. Understanding Points, Lines, Line Segments, and Rays
Competency: Identify and differentiate between basic geometrical figures.
Answers:
a)
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Point: A point represents a location. It has no length, breadth, or thickness. Example: Dot (.)
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Line: A straight path extending in both directions without end. Example: AB↔
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Line Segment: A part of a line with two endpoints. Example: AB
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Ray: A part of a line with one endpoint, extending endlessly in one direction. Example: AB→
b) Correct Answer: b) AB→
c)
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a) False (A line has no endpoints; it extends indefinitely.)
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b) False (A point has no length.)
d) Diagrams to be drawn:
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Two rays with common endpoint (O): OA→ and OB→
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Two intersecting lines: Lines AB↔ and CD↔ intersecting at point P
e) Correct Answer: a) One
2. Intersecting and Parallel Lines
Competency: Visualize intersecting and parallel lines in real life.
Answers:
a) Intersecting Lines: Lines that meet at a point.
b) Parallel Lines: Lines that never meet, even if extended. Example: Railway tracks.
c) Draw 2 pairs of parallel lines: AB‖CD and EF‖GH
d)
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a) Parallel
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b) Intersecting
e) Correct Answer: c) A is true, R is false
3. Angles and Their Types
Competency: Identify, classify, and measure angles.
Answers:
a) An angle is formed when two rays meet at a point (vertex).
b) Vertex: The common endpoint of two rays forming an angle.
c) Matching:
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Acute angle → (ii) less than 90°
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Right angle → (i) 90°
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Obtuse angle → (iii) greater than 90° and less than 180°
d) Diagrams to be drawn for each angle.
e)
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a) Reflex
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b) Straight
4. Pair of Angles
Competency: Understand complementary, supplementary, adjacent, and vertically opposite angles.
Answers:
a) Complementary angles: Sum = 90°. Example: 60° and 30°.
b) Supplementary angles: Sum = 180°. Example: 110° and 70°.
c) Complement of 35° = 55°
d) ∠Y = 180° - 60° = 120°
e) Adjacent angles diagram: Two angles sharing a common side.
5. Properties of Angles on a Straight Line and at a Point
Competency: Apply angle properties to solve problems.
Answers:
a) Sum on straight line = 180°
b) Vertically opposite angles are equal.
c) ∠B = 180° - 120° = 60°
d) Vertically opposite angle of 75° = 75°
e) If one angle is 50°, others are 50°, 130°, 130° (by vertically opposite and linear pair rules).
🧠 Competency-Based Questions
6. Application Questions
Competency: Apply geometry concepts in real-life contexts.
Answers:
a) Acute angle
b) Right angle
c) Supplementary angle of 89° = 91°
d) Freehand draw approximately 150°
e) Right angle (90° at 3 PM)
7. Assertion-Reasoning
Competency: Analyze statements logically.
Answers:
a) Correct Answer: c) A is false, R is true
b) Correct Answer: a) Both A and R are correct and R explains A
c) Correct Answer: a) Both A and R are correct and R explains A
d) Correct Answer: a) Both A and R are correct and R explains A
8. Case Study Based
Competency: Analyze geometrical concepts in practical situations.
Case Study 1:
a) Acute and obtuse angles.
b) Yes, vertically opposite angles are equal. Example: 50°-50°, 130°-130°
c) Typically 10 acute angles in a star.
Case Study 2:
a) Intersecting lines (diagonals), parallel lines (sides), right angles (corners).
b) Diagonals can form obtuse angles (more than 90°) inside rectangles.
c) Sum = 360°
9. Higher Order Thinking Skills (HOTS)
Competency: Apply reasoning and justify answers.
Answers:
a) Draw X and Y axis meeting at 90°.
b) No. Both obtuse angles > 90°. Their sum > 180°.
c) Example: Scissors blades, crossed roads.
d) Sum of other two angles = 90°
e) 3x + x = 180° ⇒ 4x = 180° ⇒ x = 45°
10. Mixed MCQs & Fill in the Blanks
Competency: Recall facts, apply properties.
Answers:
a) c) AB
b) Parallel
c) Complete/Full angle
d) One
e) Let one angle be x, other = 2x
x + 2x = 180° → 3x = 180° → x = 60°, 120°
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