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在最近一段时间的复习中,经常遇到圆锥曲线中一类斜率关系题,从同学们答题的情况看,掌握的不理想,下面,我们通过四道典型问题一起来集中突破.(注:每题第(1)问请同学们自行求解.)例1.已知抛物线C:y=ax2过点P(4,4).(I)求实数a的值;(II)设点A,B在抛物线C上,直线PA,PB的斜率分别为K1,k2,且k2-k1=1,若△AOP的面积是△AOB的面积的2倍(O为坐标原点),求直线PA的方程.解析:(I)a=14.
In the recent period of review, often encounter a type of slope conic relationship, from the students answer the situation, the grasp is not ideal, below, we focus together through four typical breakthrough. (Note: (1) Ask students to solve for themselves.) Example 1. Known parabola C: y = ax2 P (4,4). (I) Find the value of a; (II) Set point A, B On the parabola C, the slopes of the lines PA and PB are respectively K1 and k2, and k2-k1 = 1. If the area of △ AOP is twice the area of △ AOB (O is the origin of coordinates), find the equation of the line PA. Analysis: (I) a = 14.