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← 2.2 Reflection and Congruence

Lines of symmetry of plane figures

Mathematics · Grade 10 · about 40 minutes

A line of symmetry is a mirror that maps a shape onto itself. Count them for triangles, quadrilaterals and regular polygons.

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  • 10 sections of explanation, worked examples and diagrams
  • 1 practice task with hints and worked answers
  • A quiz that marks itself as you go
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Other lessons in this sub-strand

  1. Congruence
  2. Reflection
  3. SSS and SAS congruence
  4. ASA, AAS and RHS
  5. Corresponding parts of congruent triangles
  6. Constructing a reflection in a given line
  7. Reflecting figures in the axes
  8. Reflection in y = x and y = -x
  9. Reflection in x = a and y = b
  10. Properties of reflection
  11. Lines of symmetry of plane figures
  12. Finding the mirror line and symmetry in design