Supplementary Angles Practice: Find the Missing Angle (GeoGebra Interactive)

This example uses an interactive geometry figure to demonstrate the measure relationship of supplementary angles and helps learners determine a missing angle. The key math concepts are supplementary angles (two angles whose measures sum to 180°), angle measure, and geometric construction/verification. Construction-wise, it builds the angle sides with Segment and key points (e.g., A, B, C, D and related labeled points), places and manipulates the configuration using Point, and uses Rotate to position the angle accurately. It then uses Angle to label and measure the relevant angles (β, γ, etc.), optionally uses Polygon for an auxiliary shape, and leverages Vector and Translate for controlled direction/placement. Interactivity and correctness checking are handled by AngleChanger and CheckAnswer, comparing the computed angles with target/primed objects (e.g., e vs e', f vs f', etc.). Suitable for middle and high school geometry practice, classroom demonstrations, and formative assessment.