Symmetry
Overview
Symmetry is everywhere, from the wings of a butterfly to the face of a clock, and mathematics gives it a precise meaning. A shape has symmetry when part of it matches another part exactly, either by folding it over a line or by turning it about a point. Spotting symmetry lets you understand a shape's structure at a glance.
In this lesson you will count lines of symmetry and find the order of rotational symmetry for two-dimensional shapes, then extend the idea to the symmetry properties of solids such as prisms, cylinders, pyramids and cones. Clear descriptions in words make every kind of symmetry easy to identify.
Objectives
- Recognise line symmetry and order of rotational symmetry in two dimensions.
- Recognise symmetry properties of prisms, cylinders, pyramids and cones. (Extended only)
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Mind map
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Flashcards
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Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Symmetry. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- How many lines of symmetry does a square have? A. 1 B. 2 C. 3 D. 4 Answer: D
- What is the order of rotational symmetry of an equilateral triangle? A. 1 B. 2 C. 3 D. 6 Answer: C
- How many lines of symmetry does a rectangle (that is not a square) have? A. 0 B. 2 C. 3 D. 4 Answer: B
- A shape with no rotational symmetry has order of rotational symmetry equal to: A. 0 B. 1 C. 2 D. infinite Answer: B
- Which solid has an axis of symmetry of infinite order? A. cuboid B. square-based pyramid C. cone D. triangular prism Answer: C
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