Cardioid: Geometric Construction and Parametric Curve

① This GeoGebra example dynamically demonstrates the formation of a cardioid, the trajectory traced by a point on a circle as it rolls around another circle of equal radius. ② Core mathematical concepts include parametric curves, trigonometric functions (especially cosine), polar and Cartesian coordinate transformations, and the relationship between rotation and angle. ③ Construction highlights: using the Circle command to create two equal-radius circles, Segment to connect centers and moving points, Rotate to rotate segments or circles generating angle α, and Angle objects to mark rotation; key objects include A, B, c, f, α, C, β, d, g. ④ Suitable for high school or early college students to understand parametric equations, trigonometric graphs, and geometric loci, and useful for math experiments or inquiry-based learning.