Series Content LESSON 1 圓的基本術語 | Basic Terms of Circles LESSON 2 圓的弦 | Chords of a Circle LESSON 3 圓的角 | Angles in a Circle LESSON 4 弧、弦與角的關係 | Relationships among Arcs, Chords and Angles LESSON 5 圓內接四邊形 | Cyclic Quadrilaterals LESSON 6 共圓點 | Concyclic Points LESSON 7 圓的切線 | Tangents to a Circle LESSON 8 切線性質 | Tangent Properties LESSON 9 交錯弓形的圓周角 | Angles in the Alternate Segment