Angles in the Coordinate Plane: Dynamic Terminal Side

This example demonstrates how an angle is formed and measured in the Cartesian coordinate plane by dragging a movable point P. The core mathematical concepts include the standard position of an angle, its initial side, terminal side, and how the angle magnitude changes as P moves. Construction details: using GeoGebra commands Ray and Angle, with objects O (origin), A (fixed point), Initial (ray), P (movable point), Terminating (ray), and AnlgeO (the angle object). Suitable for middle or high school students learning trigonometry, general angle definitions, and coordinate geometry. It provides an interactive visual for understanding positive/negative angles and quadrant relationships.