1. Rotate an upright coin quickly (assuming the rotating shaft is in place), and the three-dimensional figure formed by rotation is.

2. To unfold the face of a cube with a side length of lc, you need to trim the edges, and the circumference of the unfolded plane figure is C. 。

3. If one side of a hexagonal prism is 5c, then the sum of all sides is.

4. An N-polygon has many diagonals starting from the vertex, and these diagonals divide the N-polygon into _ _ _ _ _ _ _ triangles.

5. As shown in the figure, after the carpenter sawed a cuboid wood with a length of 1.6m into three sections, the surface area increased by 80, so the original volume of this wood was

Second, choose one carefully and you will know gold! (4 points for each small question, * * 10 small question, ***40 points)

6. As shown in the figure, it is a geometric figure composed of several small squares and figures seen from above, so when you look at this geometric figure from the left, the geometric figure you see is ().

7. The following figure shows three shapes of a geometry, so the geometry can be ().

From the front, from the left, from above.

8. The flat expansion diagram of the uncovered cube box can be () in the figure below.

9. As shown in the figure, there are three shapes in the geometry composed of several identical small cubes, so the number of small normal bodies that make up this geometry is ().

10. As shown in the figure, the top view of the geometric figure composed of the same small cubes is displayed. The numbers in the small squares indicate the number of small cubes in this position, so the shape of the geometric figure viewed from the front is ().

1 1. As shown in the figure, the four geometries are cuboid, cylinder, sphere and triangular prism respectively, and three of these four geometries have the same geometry, so the other geometry is ().

A. Cuboid B. Cylinder

C. sphere D. triangular prism

12. The picture is an enlarged view of a cube with a Chinese character on each side, so on the surface of the cube, use? Are you welcome? The Chinese character on the reverse side is ()

A. Wen B. Ming C. Ao Deyun

13. As shown in the figure, the shape diagram of the geometric figure viewed from above is ().

14. Four pieces of cardboard with the following shapes can be folded in half according to the center line in the figure to form a straight triangular prism ().

15. Rotate around the right-angled edge as shown in the bottom left, and the shape diagram of the geometric figure obtained from the front is ().

Third, do it with your heart and you will succeed soon! (Each small question 12 points, ***5 small questions, ***60 points)

16. Cut a square in the picture so that the rest can be folded into a cube. Which small square should I cut off? Tell all the possible situations.

17. A simple geometric figure composed of some small cubes with the same size from the front and above (as shown in the figure):

(1) If the number of cubes that make up this geometry is n, then all possible values of n are.

Please draw all possible shapes of this geometry from the left.

18. As shown in the figure, a geometric figure has two shapes. Find the geometric volume (л takes 3. 14).

19. The geometry as shown in the figure consists of several identical cubes (the first layer,1; 3 on the second floor; 3, 6 floors), the area of one side of the small cube is1c. Today, the surface of this geometry is red (but there is no color at the bottom). What is the area to be colored?

20. If it is known that the line segment between two points is the shortest, can you try to solve the following problems?

Problem: It is known that there is a spider at vertex A and a bug at vertex B of the cube. As shown in the picture, please draw a shortest path from A to B on the picture, so that this little spider can catch this bug in the shortest time.

Reference answer

1. Sphere 2.7,63.30c4.n-3, N-25.326.b7.a8.d9.c10.c1.c12.a.