Sine of Obtuse Angles

This GeoGebra example demonstrates how the sine of an obtuse angle is constructed and visualized geometrically, emphasizing the relationship between an obtuse angle and its supplementary acute angle. Core mathematical concepts include trigonometry (sine function), obtuse and acute angles, angle measurement, triangle congruence and similarity, and geometric modeling on the unit circle or right triangles. The construction relies on GeoGebra commands LaTeX, Line, Vector, Intersect, Point, and Segment, together with objects such as g, text2, a, A, B, f, C, D, u, v, E, F, G, h, H, i, text1, text3, text4, and text5. Points, lines, segments, vectors, and intersections are used to build the geometric figure step by step. This resource is suitable for middle school and high school mathematics instruction, particularly for classroom demonstrations of the extension of trigonometric definitions to obtuse angles, the geometric interpretation of sine values, and related geometric construction practice.