摘要:过抛物线y2=2px(p>0)焦点F的弦AB.点A.B在抛物线准线上的射影为A1.B1.求∠A1FB1. 解:由抛物线定义及平行线性质知∠A1FB1=180°-(∠AFA1+∠BFB1) =180°-(180°-∠A1AF)-(180°-∠B1BF) =(∠A1AF+∠B1BF)=90°. 探究创新
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