心形线，是一个圆上的固定一点在它绕着与其相切且半径相同的另外一个圆周滚动时所形成的轨迹，该程序可以动态的演示心形线的生成过程，-Heart-shaped line, is a fixed point circle around it with its tangent and the radius of a circle the same rolling track being formed, the program can be a demonstration of the dynamic he