论文部分内容阅读
运用题组进行教学,可以把有关知识综合串联起来,有助于开拓学生的思路,培养综合运用的能力。本文介绍“圆锥曲线”中的两个题组。 (一)抛物线的焦点弦有着广泛的应用,围绕着焦点弦、切线、准线等可以组成很多题目。为了帮助学生理清头绪,我们首先复习统编教材上证过的两个题:(1)已知经过抛物线y~2=2px上两点P_1(x_1,y_1)和P_2(x_2,y_2)的两条切线相交于点M(x_0,y_0)。求证x_0=(y_1y_2)/(2p),y_0=(y_1+y_2)/2。(解几课本第120页第6题)(2)过抛物线y~2=2px的焦点的一条直线和这抛物线相交,两个交点的纵坐标为y_1、y_2。求证y_1y_2=-p~2。(解几课本第111页第8题)在学生掌握了这两题的证法和结论
The use of group teaching, you can put together a comprehensive knowledge, help to develop students ideas, develop comprehensive use of the ability. This article describes two topics in “Conic Curve.” (A) the focus of the parabolic chord has a wide range of applications, focusing on the chord, tangential, alignment, etc. can be composed of many topics. In order to help students sort out the clues, we first review two questions that have been approved in the textbook: (1) It is known that after two points P_1 (x_1, y_1) and P_2 (x_2, y_2) on the parabola y ~ 2 = The tangents intersect at point M (x_0, y_0). Verify that x_0 = (y_1y_2) / (2p), y_0 = (y_1 + y_2) / 2. (Solve several textbooks page 120, title 6) (2) Parabola y ~ 2 = 2px focus of a straight line and the intersection of the parabola, the two points of ordinate y_1, y_2. Verify y_1y_2 = -p ~ 2. (Solve a few textbooks page 111, eighth questions) in the students mastered the two questions of the law and conclusion