What is the point in the three dimensional space three dimensional free space

The landlord is confusing the practical with the abstract. Points, lines, and planes are all abstracted by people, and these things do not exist in real life, they are all bodies. In philosophy, a point is the smallest unit that cannot be divided, in mathematics a point is something represented by a string of coordinate values, and in physics a point is a mass "concept".

These are all things that are convenient for the study of each discipline and are prescribed by people, and to put it bluntly, they are "artificial", and if you ask the meaning of this man-made thing in real life, the question itself is meaningless, just as it is meaningless if you ask what "line" and "surface" are.

A point is the most basic figure in geometry where a dot moves into a line to form a one-dimensional space.

The line moves into a surface to form a two-dimensional space.

The surface is formed into a three-dimensional space.

3-dimensional space plus time forms 4-dimensional space.

Multidimensional space can only theoretically represent the fact that entities cannot be seen in everyday life.

A location point that has no volume but a specific location (if reference coordinates are available). In stereozology, it's the equivalent of a positional coordinate. A point is a concept that represents a very small space.

A point is a broad concept used to describe an encounter, where two straight lines of infinite thinness intersect at a minimum point

In geometry, the concepts of points, lines, surfaces, and volumes are often mentioned, that is, infinite points constitute a line, and infinite lines constitute a surface, so a point is a concept that represents a very small space

Points have no length, area, volume.

Difficult questions, call Einstein.

It depends on what kind of three-dimensional space it is.

Regardless of which one is short, let the three sides of the vertex be a, b, and c respectively (the round bridge makes do with it- - because the area of the three faces of the vertex is the root number 2, the root number 3, and the orange shirt fierce root number 6, so ab= 2 (1).

bc=√3 (2)

ac=√6 (3)

Then (1)*(2)*(3) can be obtained (abc) 2=6, then (1) 2 can collapse (ab) 2=2, and the same is true (bc) 2=3, (ac) 2=6

Then c 2 = (abc) 2 (ab) 2 = 6 2 = 3, the same way a 2 = 2, b 2 = 1

Then the diagonal length of the body = (a 2 + b 2 + c 2) = 3 + 2 + 1) = 6 If the three side areas of the common vertex are 3, 5, 15, and the method is the same as above, you can find abc = 15, so the three sides are 5, 3, 1 respectively

then the volume is 5*3*1=15

Personally, I recommend you to use the free space in the host house.

I used it, but ID verification is a bit troublesome. But the speed is very block, and there are no ads.

Highly recommended.

3. Microspace has always been rubbish, and I recently discovered a space.

The U.S. is relatively stable and free of charge but I found that one of their Hong Kong charging spaces seems to be very good.

The center of the circle should be dotted.

Don't you call the top of the round table a cone?

Don't have 4 sidesYes.

It is known that the length of the three edges with vertex a as the endpoint is 1 and the angle between the two sides is 60°, so the length of the 12 edges of the hexahedron is 1At the same time, all six sides are diamond-shaped. This is known by the known.

In addition, by connecting AC and A1C1, it can be proved that the plane AA1C1C is perpendicular to the plane ABCD (it can also be seen from the symmetry, if you want to prove it concretely, try it yourself). In this way, the angle of AC1 to the planar ABCD is CAC1.

At this point, we just need to do research.

First ac=root3. cc1=1

Seek acc1 first. To be intuitive, you can ask for it first. It is known that the three edges with vertex A as the endpoint are all 1 and the angles between the two are 60°, which can be easily solved if the perpendicular lines from A1 to AC and AD1 are made. sin∠a1ac=√11/4

So cos acc1=- 5 4, in acc1 according to the cosine theorem, we can find ac1= (4+ 15 2).

Then use the cosine theorem to find cos cac1=( 3 + 5 2) (4 + 15 2).