Unit Circle Part 2: Geometric construction for trig correspondence

This example demonstrates how points on the unit circle correspond to an angle, and how the values of trigonometric functions can be read from a geometric construction involving projections and labeled relationships. The key mathematical ideas include the unit circle, the mapping between angle and the point on the circle, and the geometric meaning of sine and cosine (and related trig values) via coordinate positions. Construction highlights: the GeoGebra command Circle is used to create the unit circle object (c); the Zip command is then used to package and manage related objects such as lines (l1, l2) together with annotation elements (text1–text4), keeping the diagram organized and emphasizing the essential geometry and labels. Suitable for late secondary school through early university learners, for instruction and interactive exploration of trigonometry through geometric visualization.