Alternate Angles: Parallel Lines and Transversal

①This GeoGebra example dynamically demonstrates that alternate interior angles formed by a transversal intersecting two parallel lines are equal. ②The core mathematical concept is the alternate angles theorem in Euclidean geometry, involving angle measurement, positional relationships, and logical reasoning. ③Construction highlights: the Line command creates parallel lines f and g, Point marks key vertices, Segment connects points to form the transversal, and Angle labels angles α, β, γ, δ; dragging points reveals the invariant equality of alternate angles. ④Suitable for middle school geometry lessons, enabling students to explore parallel line properties, verify the theorem interactively, and develop geometric intuition and dynamic investigation skills.