Geometric Discovery of sin(a+b) and cos(a+b) (Solution)

This GeoGebra example demonstrates a geometric discovery and solution for the addition formulas sin(a+b) and cos(a+b). It uses rays, points, angles, orthogonal lines, intersections, rotations, lines, and segments to build auxiliary right triangles and projection relationships, revealing how the sine and cosine of a sum can be expressed through component angles. The construction emphasizes trigonometric identities, angle composition, perpendicular projections, and dynamic geometric reasoning. It is suitable for high school trigonometry lessons, inquiry-based mathematics activities, GeoGebra demonstrations, and visual proofs of addition formulas.