作者yoolooroo (YES!!)
看板GRE_Verbal
标题Re: [问题]一题来欣M2的数学
时间Sun Jun 24 20:34:15 2007
※ 引述《hjung (D~~~~~~!!)》之铭言：
: Rught triangle PQR is to be constructed in the xy-plane so that the right
: angle is at and PR is parallel to the x-axis.
: The x- and y-coordinates of P, Q, and R are to be integers that satisfy the
: inequalitues -4≦x≦5 and 6≦y≦16.
: How many different triangles with these properties could be constructed?
: (A) 100
: (B) 1,100
: (C) 9,900
: (D)10,000
: (E)12,100
: 答案是(C)
: 算了很久算不出来 请大家帮忙了~"~
: 谢谢^^
C11取2*C10取2*4=9900
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◆ From: 122.124.65.29
1F：推 hjung:谢谢^^ 140.114.194.2 06/24 22:16
2F：推 angeline107: 为何最後*4 ??? 61.64.136.86 06/25 09:24
3F：推 hjung:因为直角三角形可以上下左右翻转 140.114.194.2 06/25 10:31