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Class 6

Chapter 2: Lines and Angles

Angles can be acute (<90°), right (=90°), obtuse (90°–180°), straight (=180°) or reflex (>180°). Pairs of angles on a straight line add up to 180°.

Learning outcomes

  • Classify angles and pairs of lines
  • Measure angles using a protractor

Activities

  • Angle-hunt around the classroom

Worked examples

Read through these first, then try the practice below.

  1. Example 1 — Linear pair

    Two angles together form a straight line. One is 65°. What is the other?

    Solution: 180° − 65° = 115°.

  2. Example 2 — Classify the angle

    Is 92° acute, right or obtuse?

    Solution: Obtuse — between 90° and 180°.

Self-do practice

Question 1 of 3 · Score 0/0

Two angles on a straight line; one is 110°. What is the other?

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