sine theorem

例句：

1. 1. Thesine theorem is a fundamentalconcept in trigonometry.
   正弦定理是三角学的基本概念。
2. 2. In thesine theorem, the sumof the angles equals twice thesine of the included angle.
   在正弦定理中，角的和等于包含角的正弦值的两倍。
3. 3. The sine theoremis used to find the length of anobject's shadow when it is caston a flat surface.
   正弦定理用于计算物体在平面上投射的影子的长度。