Because the relationship between the three sides of a triangle is that the longest third side should be less than the sum of the other two sides and greater than the difference between the other two sides.
So the experiment 1 If there is 1 cm, 2 cm? 3 cm？ You can make up 0 different triangles with toothpicks.
Experiment 2. If there is 1 cm, 2 cm? 3 cm？ 4 cm？ Toothpicks can form 1 different triangles.
Experiment 3. By analogy, 1, 2,3,4,5 can form two different triangles.
The survey results can be recorded as follows:
I don't know if there are any illustrations. It would be much easier to answer with Luo's example. Send it up first and see if the picture has been handed down for explanation. The final answer is:
When the number of experiments is n, the matching length is n=N+2(n is the matching length and n is the number of experiments).
There are rules to follow, which can be divided into two parts, that is, whether the number of experiments is odd or even, and there are rules to follow. When the measured n is an even number, the matching length is n = n+2, and the even number is the matching cm length, the number of triangles that can be formed is n = ((n-2)/2) square.
When the test n is an even number, when the matching length is n.
When the length = n+2 is even cm, the number of triangles that can be formed is n = ((n-3)/2+ 1) * ((n-3)/2).