noun
spherical trigonometry
A branch of mathematics dealing with triangles on the surface of a sphere, used in astronomy, geodesy, and navigation.
球面三角法は、天文学や測地学で重要な役割を果たす。
Spherical trigonometry plays an important role in astronomy and geodesy.
平面三角法 (plane trigonometry) deals with triangles on a flat plane, while 球面三角法 deals with triangles on a sphere.
Compound of 球面 (spherical surface) + 三角法 (trigonometry). The term is a direct calque from Western mathematics.