Trigonometry Basics: Unit Circle Sine and Cosine Construction

This GeoGebra example demonstrates the geometric construction of sine, cosine, and tangent on the unit circle, showing how trigonometric function values correspond to point coordinates and segment lengths as the angle THETA varies. Core mathematical concepts include trigonometry, the unit circle, angle measurement, similarity transformation, and the connection between circular geometry and trigonometric functions. The construction employs GeoGebra commands Intersect, Circle, Point, Segment, and Angle, using objects such as A, c, F, C, B, a, THETA, d, b, D, sine, cosine, e, E, and tangent to build a dynamic diagram linking points, circles, segments, and angles. It is suitable for middle school and high school students learning trigonometry fundamentals, supporting classroom demonstration, interactive exploration, and the bridge between unit-circle definitions and function graphing.