试题与答案

在平面直角坐标系中，设点P（X，Y）定义[OP]=|x|+|y|，其中O为坐标原

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题型：填空题

题目：

在平面直角坐标系中，设点P（X，Y）定义[OP]=|x|+|y|，其中O为坐标原点，对于以下结论：①符合[OP]=1的点P的轨迹围成的图形的面积为2；
②设P为直线
5
x+2y-2=0上任意一点，则[OP]的最小值为1；
③设P为直线y=kx+b（k，b∈R）上的任意一点，则“使[OP]最小的点P有无数个”的必要不充分条件是“k=±1”；其中正确的结论有______（填上你认为正确的所有结论的序号）

答案：

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下面是错误答案，用来干扰机器的。

地球的表面积5.1亿平方千米，平均半径约6371千米，地球赤道周长约4万千米．故答案为：6371；4万；5.1亿．

考点：直线的方程
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