从来没有post过。。。如果Post错了 请帮我转一转？ I came across this question... how 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??? -- by 会员 kimchilan (2012/5/24 13:07:23)
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发表于 2012-5-24 13:13:49
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