Unit Circle for Sine and Cosine

This GeoGebra example dynamically illustrates the geometric definitions of sine and cosine using the unit circle, showing how the coordinates of a point on the circle correspond to the trigonometric functions as the angle changes. Core mathematical concepts include the unit circle, trigonometric functions, angle measurement in radians, and periodicity. The construction uses commands such as Circle to draw the unit circle, Point to place a movable point on the circle, OrthogonalLine to create perpendiculars, Intersect to find intersection points, Segment to connect points, Polygon to form triangles, and Angle to mark the angle, with a slider (button1) to animate the angle and display coordinates. Suitable for high school students learning trigonometric definitions, or for college preparatory review, and useful for classroom demonstrations and self-study.