凡学过三角的人,誰都知道“用線段去表示三角函数”这节教材的重要性。但有的教师在教学过程中講的不深不透,容易造成学生的死記硬背現象;此如有的学生問:“正切線为什么一定画在單位圓的右边而不能画在它的左边”?有的教师回答“这是一个規定”!这样的回答当然不会使学生滿意的,甚至有的教师認 Everyone who has studied the triangle knows the importance of using the line segment to represent trigonometric functions. However, some teachers don’t speak in depth during the teaching process, which can easily cause the students’ rote memorization; this all-embracing student asks: “Why is the tangent line painted on the right side of the unit circle and not drawn on the left? Some teachers replied that “this is a rule”! Of course, this answer will not be satisfactory to students, and some teachers may even recognize it.