Isosceles Trapezium: Angles and Diagonal Relationships

This GeoGebra example dynamically demonstrates the relationships between angles and diagonal lengths in an isosceles trapezium (isosceles trapezoid). It visually shows that base angles are equal and diagonals are congruent, along with other angle relations arising from symmetry. Core math concepts include properties of isosceles trapezoids, parallel lines, triangle congruence and similarity, and measurement of angles and segments. Construction highlights: using GeoGebra commands such as Line, LineBisector, Mirror, Polygon, Segment, Angle, Intersect, Distance, and Midpoint to build a symmetric trapezoid, measure its angles and diagonals, and allow interactive dragging to verify invariant properties. Suitable for middle school to high school students learning plane geometry, quadrilateral properties, and geometric proofs, as well as for teachers demonstrating symmetry and congruence in the classroom.