1. Trigonometry is a branch of mathematics that deals with the relationships between the angles and sides of triangles.
三角学是数学的一个分支，它研究的是三角形的角和边之间的关系。
2. In trigonometry, the sine, cosine, and tangent functions are commonly used to calculate angles and distances in triangles.
在三角学中，正弦、余弦和正切函数常用来计算三角形的角度和距离。