What is the definition of a rotating surface? It is said in the book that the surface formed by a curve rotating around a fixed line in its plane is called a rotating surface. But why does a cylinder also have a rotating surface? That surface is a rotating surface
The (side) surface of a cylinder is a surface of revolution. It revolves around the cylinder
A fixed line is formed by the rotation of the line connecting the center of the upper and lower circles
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- 1. Definition of figure rotation: turning a figure_____________________ It's called rotation
- 2. Properties of the corresponding edge of a graph rotated 90 degrees
- 3. The contradiction between the definition of time length and the rotation of celestial bodies The earth's rotation cycle is 24 hours, 24 hours = 86400 seconds, but the original definition of seconds is definitely not according to 1 / 86400 of the time required for the earth's rotation cycle, so there must be errors. According to this, the error is a little every day. It can be imagined that 12 o'clock is just the time when the sun rises! I want to know how to adjust this problem What's more, a year is 365 days now, and a cycle of the earth's revolution can't be a whole day, right? There must be a small change. Even if it is adjusted by four years plus one day, it will be adjusted according to the whole day. What about the remaining small change? You can imagine that in January, the northern hemisphere is summer! The answers on the second floor and the fifth floor are not satisfactory. The others are not so good. I know it's adjusted by leap year, but it's also adjusted by the whole day. Have you seen it all day? But the error is not 1 / 4 of the whole day. What about the rest? The second floor let me know that Beijing time is set artificially. I understand that every other time, not only Beijing time (because world time should be unified), but also time zones around the world should be adjusted.
- 4. What is the relationship between people's daily living time in one day and the earth's rotation? Is it the accurate time for the earth to rotate for one cycle
- 5. Turret rotation time: 0.1 sec / division?
- 6. In a week, the rotation angle a (degrees) and the rotation time t (minutes) are the same Is this proportional? Write the analytic expression of the function Explain why the proportion is positive
- 7. What's the relationship between one revolution of the moon and one revolution of the moon around the earth Hurry up and wait online
- 8. What's the meaning of no turning
- 9. What are the common characteristics of rotation and translation
- 10. Translation concept Translate a graph, and then connect two corresponding points to a line segment. Is such a line segment called a corresponding line segment?
- 11. What is rolling planning method (meaning)
- 12. What is the definition of rotation angle
- 13. What is the nature of rotation?
- 14. The concepts and properties of translation and axisymmetric transformation
- 15. What things in life are related to technology
- 16. There are 35 students in class 5 (1) of Xinhua primary school. They asked the photo studio to take a group photo. Each student should take a photo, give it to the teacher and enlarge it. They should give it to each student How much is the charge? (25 yuan for group photo, 2 photos for free; 0.8 yuan for printing and 5.2 yuan for enlarging)
- 17. After learning Chapter 2 "special triangles", the teacher assigned a question: as shown in the figure, points m and N are on the sides of BC and Ca of the regular triangle ABC, and BM = CN, am and BN intersect at point Q. (3) if the points m and N in the question are moved to the extension line of BC and Ca, and BM = CN, can we get ∠ BQM = 60 °? Please give reasons (1) Judge whether △ ABM and △ BCN are congruent and explain the reason. (2) judge whether ∠ BQM is equal to 60 ° and explain the reason
- 18. In the class of "bisector of angle", the teacher asked the students to practice a problem. The figure of the problem is shown in the figure. BD in the figure is the bisector of ABC. While the students were busy drawing and analyzing the problem, Xiaoying suddenly said excitedly: "I have a discovery!" Originally, she felt that she had created a method to draw the acute bisector in a right triangle. Her method is as follows: take a point E on AB, make be = BC, and then draw de ⊥ AB and AC at point D, then BD is the bisector of ∠ ABC? Please give reasons
- 19. The cube with edge length a is placed in the shape shown in the figure. (1) try to find its surface area; (2) if it is placed in 10 layers, what is its surface area?
- 20. It is known that the line y = 1 / 2x + 3 intersects the two coordinate axes at two points a and B. the image of the quadratic function y = - x ^ 2 / 4 is translated left and right first, and then up and down twice, so that it passes through points a and B to find the vertex coordinates of the translated image