证明以抛物线的焦点弦为直径的圆与抛物线的准线相切
人气:389 ℃ 时间:2020-01-28 14:40:54
解答
抛物线的标准式是 y2=2px 焦点横坐标为p/2 准线横坐标为-p/2 把焦点横坐标代入抛物线中y2=p2 y=正负P 那么直径长为2P 半径为p 焦点到准线距离为p/2-(-p/2)=p 则抛物线的焦点弦为直径的圆与抛物线的准线相切
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