高考数学难点突破_难点22__轨迹方程的求法(国外英文资料).docVIP

高考数学难点突破_难点22__轨迹方程的求法(国外英文资料) The solution of the 22 locus equation of difficulty The trajectory equation of the demand curve is one of the two basic problems of analytic geometry. The trajectory equation meets a certain condition point, its essence is to use the geometric conditions of the problem set, with the coordinate into seeking the relationship between the variables. This kind of problem in addition to test students on conic definition basis the nature of knowledge and mastery, but also fully examine a variety of mathematical methods and certain reasoning ability and operation ability, so this kind of problem has become the focus of the college entrance examination, it is difficult for the students. Difficult magnetic field (assumes) A, B for two known points, point to A and M to B ratio is a constant distance lambda, trajectory equation M, and indicate what is the trajectory curve. Case study A case of 1 as shown in the figure, the known P (4, 0) is a circle in the x2+y2=36, A, B is the two point circle, and meet the angle APB=90 degrees, the trajectory equation of rectangular APBQ vertex Q. This proposition intention: the trajectory equation mainly examines the demand curve using point substitution method, is it assumes topic. Knowledge support: using the basic knowledge of plane geometry and the distance formula between two points, the trajectory equation of the midpoint of line AB is established Error analysis: desire trajectory equation of Q, should first seek the trajectory equation of R, if the students thinking is not profound, not found substantial problems, it is difficult to solve this problem. Skills and methods: explore the trajectory equation of some complicated problems, can determine the trajectory equation of a relatively easy to obtain the point, then this point as the initiative, the locus of points on the related points, obtained the trajectory equation. Solution: the midpoint set AB R coordinates (x, y), in Rt ABP, |AR|=|PR|. And becau