Triangle BCD and ACD are different only from BC and AC, so the difference of 3cm is the part where BC is longer than AC. BC is 8cm, then AC is naturally 5cm.

1-9 is divided into three groups, and the sum is equal to 15 (see Jiugong for details). There are 249, 168, 357, 267, 348 and 159, 258 and 456 groups respectively.

However, only168,249,357 and159,267,348 exist in three groups at the same time.

The sum of four numbers on a straight line is equal. In fact, the first group and the second group each take 1 number, and the third group takes 2 numbers and the sum is equal.

So it's 2657 1937? 4835? As shown in the figure (not easy to draw, but can understand)