前面讲到任意角的教学,强调了“刻画一个既有大小又有方向的量”的方法,要按照“背景—定义—度量—运算—性质”的路径,使学生经历角的概念的推广过程(就像数系的扩充一样).下面专门谈谈度量问题.首先,要引导学生认识引入弧度制的必要性.该怎么做呢?因为将角的范围推广到任意角是为了建立三角函数概念,自然想到定义一个函数有什么要求.高中把函数定义为两个实数集之间的对应关系,而实数的进位制是十进制.如果沿用锐角三角函数的 In front of the teaching of arbitrary angle, emphasizing the “portraying a volume of both size and direction ” approach, according to “background - the definition - measurement - computing - nature ” path, so that students experience the angle The concept of the promotion process (just as the expansion of the same number system.) The following specifically talk about the measurement problem .First, to guide students to understand the necessity of the introduction of radian .How to do it? Because the scope of the angle is extended to any angle The establishment of the concept of trigonometric functions, of course, naturally think of the definition of a function of any requirements. High school to define the function as a correspondence between two real numbers set, and the real number of decimal system is decimal. If the use of acute trigonometric functions