# Hollow Ellipse

- Hollow ellipse (a two-dimensional figure) has two ellipses with a conic section or a stretched circle.
- The major axis is always the longest axis in an ellipse.
- The minor axis is always the shortest axis in an ellipse.

## Hollow ellipse Area formula |
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\(\large{ A_{area} = \pi \; \left( a \; b - e \; f \right) }\) | ||

Symbol |
English |
Metric |

\(\large{ A }\) = area | \(\large{ in^2 }\) | \(\large{ mm^2 }\) |

\(\large{ a }\) = length semi-major axis | \(\large{ in }\) | \(\large{ mm }\) |

\(\large{ b }\) = length semi-minor axis | \(\large{ in }\) | \(\large{ mm }\) |

\(\large{ e }\) = length inner semi-major axis | \(\large{ in }\) | \(\large{ mm }\) |

\(\large{ f }\) = length inner semi-minor axis | \(\large{ in }\) | \(\large{ mm }\) |

\(\large{ \pi }\) = Pi | \(\large{3.141 592 653 ...}\) |

## Hollow ellipse Inner Semi-major Axis Length formula |
||

\(\large{ e = a-g }\) | ||

Symbol |
English |
Metric |

\(\large{ a }\) = length semi-major axis | \(\large{ in }\) | \(\large{ mm }\) |

\(\large{ b }\) = length semi-minor axis | \(\large{ in }\) | \(\large{ mm }\) |

\(\large{ g }\) = ring width | \(\large{ in }\) | \(\large{ mm }\) |

## Hollow ellipse Inner Semi-minor Axis Length formula |
||

\(\large{ f = b-g }\) | ||

Symbol |
English |
Metric |

\(\large{ a }\) = length semi-major axis | \(\large{ in }\) | \(\large{ mm }\) |

\(\large{ b }\) = length semi-minor axis | \(\large{ in }\) | \(\large{ mm }\) |

\(\large{ g }\) = ring width | \(\large{ in }\) | \(\large{ mm }\) |