Revisiting Right Triangles with the Unit Circle

This example demonstrates the geometric foundations behind right-triangle facts by linking a right triangle to the unit circle, making the connection between an angle and its associated sine/cosine values visually clear. Key concepts include right-triangle angle–side relationships, the geometric meaning of trigonometric quantities (sin and cos), and how the position of an angle on the unit circle corresponds to function values. The construction should center on building a right triangle and measuring its relevant angles, then drawing the unit circle in a coordinate plane and using the radius endpoint/angle measure to drive the relationships to trigonometry. Since no explicit GeoGebra commands were provided in the source (no construction summary), the construction focus is inferred from the listed themes: geometric construction of triangle and angles, unit circle setup, and (optionally) dynamic updates such as angle sliders for interactive learning. Suitable for middle/high school mathematics review, classroom demonstrations, and student self-study on right triangles and trigonometric interpretations.