Angle Relationships within Parallel Lines

This GeoGebra example demonstrates the angle relationships formed when two parallel lines are intersected by a transversal. Using the Line command to construct parallel lines a and b intersected by line c, and Point command to mark intersection points A, B, C, D, with text labels showing corresponding angles, alternate interior angles, consecutive interior angles, and vertical angles. Users can drag points or adjust line positions to observe how angle measures change while maintaining their relationships. Ideal for middle school students in grades 7-9 learning parallel line properties, and for teachers as a visual aid in geometry instruction.