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为了避免引进直线的法线式方程,中学教材中关于点到直线的距离公式是以绝对值的形式出现的,至于去掉绝对值符号后正负号的选择问题,教材避而未谈。考虑到这部分内容现已移到高中《解析几何》中,而且学生学过了“二元一次不等式表示的区域”,所以可以把公式中去掉绝对值符号后正负号的选择方法作个介绍。首先,如课本所介绍的那样导出公式:平面内一点 P(x_0,y_0)到一条直线 Ax+By+C=0的
In order to avoid the introduction of a straight-line normal equation, the middle school textbook on the point-to-line distance formula appears in the form of absolute value, as to remove the sign of the absolute sign after the choice of the problem, teaching materials not to mention. Considering that this part has now been moved to High School “Analytic Geometry,” and students have learned “Binary One-Time Inequality-Representing Regions,” one can introduce the formula for selecting the sign of an absolute sign . First, export the formula as described in the textbook: a point P (x_0, y_0) in the plane to a straight line Ax + By + C = 0