Rectangle Construction and Perpendicular Relationship Demonstration

This GeoGebra example demonstrates how to construct a rectangle and visually illustrates that its adjacent sides are perpendicular while its opposite sides are parallel. The core mathematical concepts involved include polygons (rectangles), angles (right angles), and the properties and criteria of perpendicular and parallel lines in Euclidean plane geometry. The construction uses GeoGebra commands Segment, OrthogonalLine, Point, Line, Intersect, and Angle, together with objects A, B, C, D, lines f, g, h, i, j, k, l, and angle α to position the rectangle’s vertices and draw its sides. It is appropriate for middle school geometry instruction, teacher-led classroom demonstrations, and independent student exploration of planar figure construction and property verification.