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识字一二千,出书三四篇。年届五六十,憋诗七八年。带徒九十届,桃李百花鲜。难求千般好,过好几万天。

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平面曲线—环锁线【引用】

2012-08-19 10:14:18| 分类：默认分类 | 标签： |举报 |字号大中小订阅

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曲线是使PM1=PM2=OP的点M1，M2的轨迹(P为y轴上一点，M1，M2在过A，P两点的射线上)。

方程：

y2=x2(a-x)/(a+x)

或

x=a(1-t2)/(1+t2)

y=at(1-t2)/(1+t2)

t=tgθ

或

ρ=a*cos2φ/cosφ

顶点 A(a,0)

节点 O(0,0)

渐近线 x=-a

圈套所围成的面积 S1=2a2-π/2*a2

曲线与渐近线之间的面积 S2=2a2+π/2*a2

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