Parallelogram Construction with Angle Annotation

① This GeoGebra example demonstrates the construction of a parallelogram, showing its vertices, sides, and angles dynamically. ② Core mathematical concepts include the definition of a parallelogram (opposite sides parallel and equal), properties of diagonals, interior angle relationships, and rotational symmetry. ③ Construction details: uses Segment command to draw sides, Rotate command to create parallel sides, and Angle command to mark angles; objects include points A, B, C, D, E, F, segments a, b, c, d, e, f, g, h, and multiple angle variables (α, β, γ, etc.) with text labels, ensuring accuracy through rotation and angle measurement. ④ Suitable for middle school geometry lessons, helping students understand parallelogram properties, angle relationships, and dynamic construction methods; also useful for teacher demonstrations.