三条边均为正整数,且最长边为 11 的三角形有( )个。A.21 B.23 C.25 D.36

作者: tihaiku 人气: - 评论: 0
问题 三条边均为正整数,且最长边为 11 的三角形有( )个。
选项 A.21 B.23 C.25 D.36
答案 C
解析 解析:另两条边的和要大于 11,且每条边都不能超过 11,符合条件的数对有: 2,10; 3,9; 3,10; 4,8; 4,9; 4,10; 5,7; 5,8;...;5,10; 6,6; 6,7;...;6,10; 7,7; 7,8;...;7,10; 8,8; 8,9; 9,10; 9,9; 9,10; 10,10; 所以一共有 1+2+3+4+5+4+3+2+1=25(种)

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