You dare to question these review materials, which shows that you are a very diligent and clever student. I applaud your behavior!

But when the polygon at the bottom is a regular polygon and the projection from the vertex to the bottom is in the center of the regular polygon at the bottom, it is called a regular pyramid. The regular pyramid has many characteristics. Studying the basic characteristics of the regular pyramid conforms to the cognitive law from special to general. Because many features of the regular pyramid are not applicable to the general pyramid, we have learned the method of studying the problem by studying the special features of the regular pyramid, and we can also discuss the general pyramid.

In the nature of a regular pyramid, it is not only necessary to understand the line-plane relationship here through spatial imagination, but also because there are two right triangles, the six quantities here have the relationship of four pythagorean theorems. For example, (drawing is not supported here, I'll tell you that you can draw in my narrative order), P-ABCDE is a regular pentagonal pyramid, O is the projection of the bottom of vertex P, and it is the center of the regular pentagonal bottom, OM⊥BC, so M is the midpoint of BC, and PM is the height △PBC on the bottom of the side, which is an oblique height of the regular pentagonal pyramid. Here, the right triangle has

PB2=PO2+OB2 (the square of the side is equal to the sum of the square of the radius of the cone and the square of the regular polygon at the bottom);

PB2=PM2+BM2 (the square of the side is equal to the sum of the square of the inclined height plane and the square of the half-length of the regular polygon at the bottom);

PM2=PO2+OM2 (the square of the inclined height is equal to the sum of the square of the cone height and the square of the far point of the regular polygon at the bottom);

OB2=OM2+MB2 (the square of the radius of the regular polygon at the bottom is equal to the sum of the square of apothem and the square of the half-length).

When solving the pyramid problem, whether it is to calculate the problem or prove the problem, as long as we grasp the four right-angled triangles mentioned above, we will master the key to solving the problem, so we must pay full attention to these four right-angled triangles, but unlike rote learning, we can use them flexibly according to actual problems on the basis of understanding, and achieve the goal of cultivating our ability by solving various pyramid problems.

When solving the pyramid problem, whether it is to calculate the problem or prove the problem, as long as we grasp the four right-angled triangles mentioned above, we will master the key to solving the problem, so we must pay full attention to these four right-angled triangles, but unlike rote learning, we can use them flexibly according to actual problems on the basis of understanding, and achieve the goal of cultivating our ability by solving various pyramid problems.

As for your "Special Reminder:" A pyramid with a regular polygon at the bottom and a congruent triangles at the side is not necessarily a regular pyramid ",it does not meet the requirements but is not a counterexample of a regular pyramid!

In other words, there is a serious mistake in the language of the "special reminder" in the Century Gold List. _ _ _ The bottom is a regular polygon with all sides equal (the word isosceles should be added here). One of the properties of a triangular pyramid is that all sides of a regular pyramid are equal and all sides are congruent isosceles triangles!

In my opinion, the review materials you used in the Century Gold List are either pirated, misprinted or omitted by the editor.

The current review materials are mixed, and the good and the bad are mixed, misleading children! I really need someone like you to identify it carefully.

Finally, I wish you excellent results in the college entrance examination and become the champion!