Definition of Complementary Angles: Dynamic Geometric Construction

This GeoGebra applet demonstrates the definition of complementary angles—two angles whose measures add up to 90 degrees—through an interactive geometric construction. Core mathematical concepts include complementary angles, angle measurement, right angles, and the relationship between angle sums and right angles. The construction employs GeoGebra commands such as Line, Point, OrthogonalLine, Segment, Rotate, Angle, and Ray, involving objects A, B, a, C, α, D₁, b, d, D, e, E, β, c, γ, T1, T2, T4, and text1. By constructing orthogonal lines, rotating segments, and drawing rays, the example visually verifies that the two constructed angles remain complementary as objects are manipulated. Suitable for middle school geometry instruction, classroom demonstrations, and student-centered exploration of angle relationships.