大家知道:平面直角坐标系中两条垂直直线的倾斜角之差的绝对值等于90°.若将这一简单的结论与直线的参数方程综合运用,能给某些高考题的解答带来便捷,有时还可以有效地回避对动直线斜率存在性的讨论.下面举例说明.例1(2016年全国高考题)如图1,设圆x~2+y~2+2x-15=0的圆心为A,直线l过点B(1,0)且与x轴不重合,l交圆A于C,D两点, We all know: Plane Cartesian coordinate system, the absolute value of the difference between the two vertical straight line angle equal to 90. If you combine this simple conclusion with the linear equation of the equation can give some answer to the college entrance examination questions to bring convenience , And sometimes can effectively avoid the discussion of the existence of the slope of the moving discussion .Examples .Example 1 (2016 national entrance examination) as shown in Figure 1, set the circle x ~ 2 + y ~ 2 + 2x-15 = 0 center For A, the line l too point B (1,0) and does not coincide with the x-axis, l round A in C, D two points,