Parabola (Focus / Directrix) Dynamic Construction

① This example demonstrates the definition of a parabola as the locus of points equidistant from a fixed point (focus F) and a fixed line (directrix d). ② The core mathematical concept is the conic section parabola, involving focus, directrix, axis of symmetry, and the quadratic function graph. ③ Construction details: using GeoGebra commands Point to create focus and points on the directrix, Segment to draw segments, OrthogonalLine to construct perpendiculars, and Intersect to find intersection points; sliders or parameters control the focus position and distance to the directrix, generating moving points on the parabola and their trace. ④ Suitable for high school analytic geometry or introductory college geometry courses, providing an intuitive understanding of the parabola's standard equation and geometric properties, and useful for teacher demonstrations or student self-exploration.