trigonometry
noun [ U ] uk/ˌtrɪɡ.əˈnɒm.ə.tri/ us/ˌtrɪɡ.əˈnɑː.mə.tri/ (informal trig)
（数学中的）三角学
a type of mathematics that deals with the relationship between the angles and sides of triangles, used in measuring the height of buildings, mountains, etc.
Trigonometry concerns the functions of angles, such as sine, cosine, and tangent. 三角学研究的是角的函数，例如正弦、余弦和正切。