Constructing a Perpendicular Line through a Point Not on the Line

This GeoGebra example demonstrates the classical straightedge-and-compass construction of a perpendicular line passing through a given external point E to a given line f. It covers core geometry concepts such as perpendicularity, right angles, the shortest distance from a point to a line, and Euclidean construction principles. The construction uses GeoGebra commands and objects including Segment to define line f via points A and B, point E located off the line, and the resulting perpendicular line intersecting f at foot point C. Suitable for middle school and high school geometry courses, this interactive example supports classroom instruction, self-paced learning, and dynamic geometry exploration of perpendicular line construction.