a plane curve generated by the locus of a point on a line at a fixed distance from the point of intersection of the line with a fixed circle, as the line revolves about a point on the circumference of the circle. Equation: r = a cosθ + b.
a heart-shaped curve generated by a point lying on a line at a fixed distance from the intersection of the line with a fixed circle, the line rotating about a point on the circumference of the circle