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问题:已知直线l经过点P(x_0,y_0),倾斜角为α,建立直线l的参数方程。笔者所见的不同版本的教材中,建立直线l的参数方程,都规定了直线l的正方向,即当直线l与x轴不平行时,l向上的方向为正方向;当直线l与x轴平行时,x轴的正方向是l的正方向。同时又引入了有向线段的数量的概念。这样的规定给教师的讲授和学生的理解带来了许多困惑。困惑1:在学习向量时都没有规定向量的正方
Problem: It is known that the straight line l passes the point P (x_0, y_0) with the inclination angle α, and establishes the parameter equation of the straight line l. I see the different versions of the textbook, the establishment of a straight line l parameter equations, are provided for the positive direction of the straight line l, that is, when the straight line l and x-axis is not parallel, l upward direction is the positive direction; when the straight line l and x When the axes are parallel, the positive direction of the x axis is the positive direction of l. At the same time, the concept of the number of directed segments is introduced. Such provisions bring many confusion to the teacher’s teaching and student’s understanding. Puzzled 1: There is no square of the vector specified when learning vectors