# Epitrochoid (X-coordinate of a point)

## Description

An epitrochoid is a roulette traced by a point attached to an external circle rolling around the outside of a fixed l circle , where the point is at a distance from the center of the exterior circle.

Related formulas## Variables

x | The x-coordinate of the point (dimensionless) |

R | Radius of the fixed circle (dimensionless) |

r | Radius of the circle rolling around the outside of the fixed circle (dimensionless) |

θ | The parameter (depented on the angle) (dimensionless) |

d | The distance from the center of the exterior circle. (dimensionless) |