小饭替狗狗主人开贴哈~谢谢kimchilan~~^^

泾渭不凡

从来没有post过。。。如果Post错了 请帮我转一转？

I came across this question...

how many sets of two points in 3-dimensional space can have a distance of 5sqrt3?
A. 0
B. 1
C. 5
D. 8
E. more than 8 (A-D 具体数字不清楚。。。E应该是对的）

思路（不知道对不对）： 5sqrt3 = sqrt of 75, distance between two points in 3D = sqrt [(x2-x1)^2+(y2-y1)^2+(z2-z1)^2] this means that 75 should be made up of three squares, which would be 49, 25, and 1. to get 49, 25, and 1, (x2-x1) or (y2-y1) or (z2-z1) could be either 9/-9, 5/-5, or 1/-1...given all these possibilities, there should be more than 8 sets???

                                                 --------kimchilan
====================================================
谢谢亲，狗狗主人主页链接：http://forum.chasedream.com/space/732245.html

livia2012

没明白，求解释..

zhaolu

什么意思？？

泾渭不凡

从来没有post过。。。如果Post错了 请帮我转一转？

I came across this question...

how many sets of two points in 3-dimensional space can have a distance of 5sqrt3?
A. 0
B. 1
C. 5
D. 8
E. more than 8 (A-D 具体数字不清楚。。。E应该是对的）

思路（不知道对不对）： 5sqrt3 = sqrt of 75, distance between two points in 3D = sqrt [(x2-x1)^2+(y2-y1)^2+(z2-z1)^2] this means that 75 should be made up of three squares, which would be 49, 25, and 1. to get 49, 25, and 1, (x2-x1) or (y2-y1) or (z2-z1) could be either 9/-9, 5/-5, or 1/-1...given all these possibilities, there should be more than 8 sets???

                                                 --------kimchilan
====================================================
谢谢亲，狗狗主人主页链接：http://forum.chasedream.com/space/732245.html

-- by 会员 泾渭不凡 (2012/5/24 15:09:16)

题目：在三维立体空间两点间的距离是5倍根号3，问这两点的坐标组合有几个。
小饭选E。同狗主。
个人理解：就是空间想象一下~
                将长度为5倍根号3的小树枝在三维空间中随便放置。。。题目没有给区间设定的条件。。。应该有无穷多种放法。。。个人认为选E~~~要是题目有区间设定就另当别论了。
                大家可以关注一下讨论稿怎样解析~
open to discuss

泾渭不凡

啊哈哈哈哈~~~我变精华啦~~~啊哈哈哈~~~

lizzieonline

顶这个，继续求讲解，这个不该是个四面体么