如图，平面β与圆锥面的轴l垂直，则交线是什么曲线？设圆锥底面半径为R，高为h，顶点S到截面β的距离为h1，（R，h，h1均为正常数）.

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如图，平面β与圆锥面的轴l垂直，则交线是什么曲线？设圆锥底面半径为R，高为h，顶点S到截面β的距离为h₁，（R，h，h₁均为正常数）.

上一题下一题 0.0难度选择题更新时间:2012-09-21 04:37:57

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解答：因为l⊥β（垂足为O₁），

所以平面β//⊙O所在的平面.

设P为交线上的任意一点，

过点P作圆锥的母线SQ，

连接PO₁，QO，

则PO为平面SQO与平面β的交线，

QO为平面SQO与⊙O所在的平面的交线.

所以PO₁//QO.于是 .

即 .因此

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