Reference Angle in the Second Quadrant Demo

This example demonstrates how to find the reference angle by dragging an angle in the second quadrant and comparing the resulting coordinates. It covers core trigonometry concepts such as sine, cosine, tangent, the definition of a reference angle, coordinate relationships on the unit circle, and quadrant symmetry. The construction uses GeoGebra commands Intersect, Circle, Point, Segment, Angle, Mirror, and OrthogonalLine to create the unit circle, angle rays, mirrored points, and coordinate labels (objects A, c, P, α, P', A', β, etc.). It is suitable for high‑school trigonometry lessons, college‑prep review, and self‑study, serving as an interactive classroom tool or online learning resource.