一到数学PREP

笑脸多多1003

A certain circular area has its center at point and has radius 4, and points X and Y lie in the same plane as the circular area. Does point Y lie outside the circular area?

1.The distance between point P and point X is 4.5

2.The distance between point X and point Y is 9
答案选C，我怎么觉得选E啊？麻烦哪个NN分析一下~~

lauchen

以圆心p再画一个4.5为半径的园，可知这个园上的点（满足PX=4.5）与小圆内任何点之间的距离都小于或等于8.5，所以一定在小圆（半径为4）外

fly12404

樓上挺正確的
不過 有另一種想法: )
用X來當圓心劃一個九為半徑的圓 圓上任一點為y
可發現P小圓在裏頭
所以y不在P圓內
這樣可能比較好想: )

笑脸多多1003

对的噶~~谢谢两位~~~