The Unit Circle and Sine Function

① This example dynamically demonstrates how the sine function value changes with the angle as a point moves around the unit circle, linking geometry to the function graph. ② Core mathematical concepts include the unit circle definition of sine, angle measurement in radians, and the geometric interpretation of trigonometric lines. ③ Construction highlights: using GeoGebra commands such as Intersect, Circle, Point, Angle, and Segment to build the circle, intersection points, angles, and segments; a slider and button control the animation, while ShowTrace and animate enable tracing the point's path to generate the sine curve. ④ Suitable for high school trigonometry lessons, pre-calculus courses, or teacher demonstrations, helping students grasp the periodicity, amplitude, and phase of the sine function through visual intuition.