Spherical triangle

...There are three points A, B, and C on a sphere, and they are not on the circumference of the same great circle, and none of the two are antipodes. In this case, the spherical figure created by is called a spherical triangle ABC, with A, B, and C called its vertices and A called its sides. The angle made by a half line tangent to the side at vertex A is called vertex angle A, and vertex angles B and C are defined similarly. ...

*Some of the terminology explanations that mention "spherical triangle" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…球面上に3点A,B,Cがあり，これらは同一の大円の周上になく，いずれの二つも対心点でないとする。このとき，の作る球面上の図形を，球面三角形spherical triangleABCといい，A,B,Cをその頂点，をその辺という。頂点Aにおいて辺に接する半直線のなす角を頂角Aといい，同様に頂角B,Cを定義する。…

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出典｜株式会社平凡社世界大百科事典 第２版について | 情報