The contents of the Mathematics Dragon Boat Festival handwritten newspaper are as follows:

1. Zongzi is an indispensable traditional food during the Dragon Boat Festival. Chinese Zongzi not only has rich and varied fillings, but also comes in various shapes. Bamboo tube-shaped, rectangular, conical, pyramid-shaped, triangular, etc., but the most common one is the "four-corner zongzi", which is a triangular tetrahedral zongzi. Why are the zongzi triangular?

2. Mathematical experts will say: Triangles are more stable. Foodies say: You can eat the filling in one bite with triangular rice dumplings! Saving on materials: The materials used to make rice dumplings vary from place to place, but they are basically the leaves of plants. The leaves are wide and long and tough, but they are leaves after all, and their width is limited. The triangular wrapping method only requires 1 or 2 leaves, while the rectangular shape requires about 3 or 4 leaves. Therefore, wrapping the rice dumplings in a tetrahedron shape can save raw materials without losing the fullness.

3. Reasonable shape: Complete leaves can be used on all four sides of the triangular rice dumpling, and no unnecessary bending is required. If the rice dumpling is made into a square, then any one surface must be connected to the other surfaces. To prevent the rice from leaking out, you need to fold the leaves and buckle them inward. The leaves are tough along the direction of the plant fibers, but they are easy to break in the vertical direction.

From a geometric point of view, let’s analyze the doorway in Zongzi:

First of all, unlike the instability of parallelepipeds (for example, the cubic frame can shake left and right), the properties of tetrahedrons It is very stable. As long as the lengths of the six edges are determined, a unique tetrahedron can be assembled. Therefore, tetrahedral rice dumplings are less likely to deform.

Although the four-cornered rice dumplings are not necessarily regular tetrahedrons, the four faces are usually the same isosceles triangles. If you take apart the surface of this tetrahedron, you can get two equal rhombuses, which means using two A similar slender leaf can just wrap it up and make the best use of it.

Another characteristic of the regular tetrahedron is that it has four threefold rotational symmetry axes and six symmetry planes. Each two opposite sides are perpendicular to each other. This shows that no matter how it is placed in the container, , the rice dumplings all look like they are lying flat on their backs neatly, without giving people the impression of lying on their sides.

The right triangular pyramid also has a center of gravity, which is also the center of its circumscribed sphere and inscribed sphere. It is on the line connecting the vertex and the center of gravity of the base. Divide this height into 3:1, that is, It's a quarter of the way off the ground. Therefore, if you use toothpicks or chopsticks to tie up the rice dumplings and find this point, you can best ensure that the force is even and will not fall or break easily. A small tetrahedral rice dumpling contains so much geometric knowledge.