Symmetry Properties of Circles

Yoong Kheong, Sep 8, 2014

The basic interactive materials serve 2 purposes in teaching and learning of symmetry properties of circle: 1. Enable teachers to use it to illustrate the symmetry properties of circle, 2. Enable students to use it for exploratory purposes.


  • 1. Equal chords are equidistant from the centre of the circle
  • 2. Perpendicular bisector of a chord passes through the centre
  • 3. Tangents from the external points are equal in length
  • 4. Angle between tangents from external point
  • 5. SPC: Question 1
  • 6. SPC: Question 2
  • 7. SPC: Question 3
  • 8. SPC: Question 4
  • 9. SPC: Question 5

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Equal chords are equidistant from the centre of the circle

[b]Sliders for changing the following:[/b][br]1. Radius of the circle,[br]2. Length of OX and OY and,[br][br][b]Red dots for rotating the respective chords:[/b][br]1. CD and AB.[br][br][b]Pre-requisite knowledge and terms:[/b] Pythagoras Theorem, Perpendicular bisector, Radius, Chords, Equidistant[br][br][b]Task:[/b] Rotate the point X and point Y accordingly for Q1[br][br][b]Q1.[/b] Observe that there are two chords, AB and CD. What is the circumstance/situation will the chord CD and AB be equal?
– Yoong Kheong

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