The curve which is the Envelope of reflected rays.

Cardioid | Cusp of Cardioid | Nephroid |

Circle | not on Circumference | Limaçon |

Circle | on Circumference | Cardioid |

Circle | point at | Nephroid |

Cissoid of Diocles | Focus | Cardioid |

one arch of a Cycloid | rays Perpendicular axis | two arches of a Cycloid |

Deltoid | point at infinity | Astroid |

rays Parallel axis | Catenary | |

Logarithmic Spiral | Origin | equal Logarithmic Spiral |

Parabola | rays Perpendicular axis | Tschirnhausen Cubic |

Quadrifolium | center | Astroid |

Tschirnhausen Cubic | Focus | Semicubical Parabola |

**References**

Lawrence, J. D. *A Catalog of Special Plane Curves.* New York: Dover, pp. 60 and 207, 1972.

© 1996-9

1999-05-26