Given is a parabola, defined by its focus point [math] F[/math] and [math] directrix [/math]. We perform inversion with respect to the circle with center [math]O_c[/math] and radius r. Point D is a point on the circle. We can change the radius [math]r[/math] by dragging [math]D[/math]. Point [math]M[/math] is a random point on the parabola. Point [math]M'[/math] is the image of [math]M[/math] under inversion with respect to the above circle ([math] O_cM \cdot O_cM' = r^2[/math]).[br]As [math]M[/math] moves along the parabola, [math]M'[/math] will draw the locus of the inverse of the parabola. [br][b]If the center of the circle is in the focus of the parabola, the inverse of the parabola is a Limaçon with a cusp (a Cardioid). [/b][br][list]