- Circles
- Circumference of Circles
- Area of Circles
- Exploring the Equation of a Circle
- Circle with Center and Radius
- Property of a tangent
- Definition of Tangent
- Rolling Coin 滾動的硬幣
- circle theorem 1a
- Radius perpendicular bisector of chord
- Circles & Their line segments
- Circle Theorem 1 - Angle at the Centre
- Circle Theorem 2 - Angles in a Semicircle
- Circle Theorem 3 - Angles in the Same Segment
- Circle Theorem 4 - Cyclic Quadrilateral
- Circle Theorem 5 - Radius to a Tangent
- Circle Theorem 6 - Tangents from a Point to a Circle
- Circle Theorem 7 - Tangents from a Point to a Circle II
- Circle Theorem 8 - Alternate Segment Theorem
