Unit Circle Point and Angle

This GeoGebra applet demonstrates how a point moves on the unit circle as its central angle α changes. It visualizes the coordinates (cos α, sin α) of the point and shows the relationship between the angle and the trigonometric functions. The construction uses the commands Point, Intersect, Segment, and Angle: the unit circle is defined by equation eq1, point A is created on the circle, segment AB connects the origin to A, and angle α is measured. A slider can be adjusted to change α, allowing interactive exploration of the circular motion. This example is suitable for high‑school students learning trigonometry and coordinate geometry, and also serves as a visual aid for calculus lessons introducing derivatives of parametric functions.