谢谢Treenewbee!解题高手!
直角(直角边是整数)三角形,在3条边(直角边在整数位置)上取3个点,
可以把直角三角形分成了4个小三角形,要求4个三角形面积都是正整数。
当较长直角边(不可以相等)=n时,有a(n)种分法(不允许翻转)。n=1,2,3,4,5,6,7,8,9,....
参考《数学中国论坛-数学期刊-几何教授的几何趣题》
Table[Length@Flatten@Table[Solve[{s1 == x*y/2, s2 == (n - x) (n - z) k/(2 n),
s3 == z (k - y)/2, s4 == n*k/2 - s1 - s2 - s3, s1 > 0, s2 > 0, s3 > 0, s4 > 0},
{s1, s2, s3, s4}, Integers], {z, 1, n - 1}, {y, 1, k - 1}, {x, 1, n - 1}]/4, {n, 1, 19}, {k, 1, n - 1}]
{{}, {0}, {0, 0}, {0, 1, 0}, {0, 0, 0, 0}, {0, 0, 14, 9, 4}, {0, 0, 0, 0, 0, 0}, {0, 5, 2, 35, 4, 25, 6},
{0, 1, 0, 6, 0, 77, 0, 16}, {0, 0, 4, 17, 104, 16, 12, 51, 16}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 9, 44, 55, 24, 173, 36, 207, 176, 113, 60}, {0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0},
{0, 0, 6, 25, 12, 24, 342, 75, 24, 48, 30, 125, 36},
{0, 4, 0, 24, 0, 143, 0, 64, 0, 504, 0, 338, 0, 124},
{0, 17, 10, 115, 20, 85, 30, 487, 40, 153, 50, 443, 60, 221, 70},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
{0, 4, 92, 57, 40, 284, 60, 163, 800, 132, 100, 893, 120, 196, 644, 375, 160},
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}
如何把这些数合并成19个数?谢谢Treenewbee! |