| __Encyclopedia :: encyclopedia : Non-euclidean geometry__ *(Site not responding. Last check: )* |

| | In **Euclidean** **geometry**, however, the lines remain at a constant distance, while in hyperbolic **geometry** they "curve away" from each other, increasing their distance as one moves farther from the point of intersection with the common perpendicular. |

| | While **Euclidean** **geometry** (named for the Greek mathematician Euclid) includes some of the oldest known mathematics, non-Euclidean **geometries** were not widely accepted as legitimate until the 19th century. |

| | **Euclidean** **geometry** is modelled by our notion of a "flat plane." The simplest model for elliptic **geometry** is a sphere, where lines are "great circles" (such as the equator or the meridians on a globe), and points opposite each other are identified (considered to be the same). |

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