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人教A版(以下同)选修4-4第二讲介绍了圆的参数方程、椭圆的参数方程及其简单的应用.事实上,圆与椭圆的参数方程本质上是通过三角代换,可将直线与圆、直线与椭圆的综合性问题(如求线段的长度、点到线的距离、多边形的面积等问题)转化为三角函数来处理.选修4-4第28页例1与选修2-1第47页例7是同一类型试题,例7给出的解法是作出直线l与椭圆,观察图形,利用平行于直线l且与椭圆只有一个交点的直线的m,再求出相应的最小距离,而例1则是利用椭圆的参数方程,将原问题转化为三角函数求最
People teach A version (the same below) Elective 4-4 The second part introduces the circle parameter equation, the ellipse parameter equation and its simple application.In fact, the circle and the ellipse parameter equation is essentially by the triangular substitution, can Convert straight lines to circles, straight lines and ellipses (such as the length of line segments, the distance between points and lines, the area of polygons, etc.) into a trigonometric function to deal with Elective 4-4 Page 28 Example 1 and Elective 2 Example 7 is the same type of questions, Example 7 gives the solution is to make a straight line l and ellipse, observe the graph, using a parallel to the straight line l and the ellipse intersects a straight line m, and then find the corresponding minimum Distance, and Example 1 is the use of elliptic parametric equation, the original problem into trigonometric function for the most