Definition of intersection: the set consisting of all elements belonging to set A and set B is called intersection of A and B. Express: A∩B Pronunciation: A to B.
We usually use uppercase Latin letters A, B, C, … to represent the set, and lowercase Latin letters A, B, C, … to represent the elements in the set. If a is an element of set A, it is said that A belongs to set A, marked as A ∈ A; If A is not an element in the set A, it is said that A does not belong to the set A, and it is recorded as a∈ (add a slash on ∈, which is similar to = and ≦) A. For example, we use A to represent the set of "1~20 all prime numbers", with 3 ∈ a, which is read in mathematics. For example, a∈A can be read as: small A belongs to big A.
Meaning: Several figures that can completely overlap are called congruent figures.
∽ Similarity If two figures are equal in shape but not necessarily equal in size, then the two figures are similar.
A mathematical symbol ⌒ arc represents an arc.
⊥ perpendicular to ⊥ vertical x ⊥ y means that x is perpendicular to y; The more general X is orthogonal to Y. If l⊥m and m⊥n, then L || n 。
∥ Parallel to//:Mathematical symbol, * * line vector. If the angle between vector A and vector B is equal to 0 or π, it is called * * line between vector A and vector B. The zero vector marked as a//b/B can coincide with the straight line where the directed line segment of any vector a*** line vector is located, that is, the 0//A. * * line vector can also be used. //:Also called double vertical lines, it is indicated by//when giving meaning to paragraphs.
∝ Proportional a∝b means that A and B are in direct proportion. For example, in v=s/t, V is proportional to S, so we can write V ∝ S. When A is inversely proportional to B, we often write A ∝1/B. This symbol "∝" (compare "∞") indicates that the physical quantities on both sides have a certain proportional relationship, including positive and inverse proportions. This symbol is sometimes used to clearly or concisely express the relationship between certain quantities. For example, the linear resistance r of a conductor is directly proportional to the length l of the conductor, which can be expressed as: R∝L, and inversely proportional to the cross-sectional area s of the conductor, which can be expressed as: r ∝1/s. We know that it should also be related to the resistivity ρ of the material used to make the conductor.
The infinite Mobius belt is often regarded as the creative source of the infinite symbol "∞", because if someone stands on the surface of a huge Mobius belt and walks along the "road" he can see, he will never stop. But this is an untrue rumor, because "∞" was invented before Mobius belt.
∮ Chapter Curve Integration (Closed Path) For example, ∮ F. ds L (F is a vector function, L is its integration path (closed curve), ds represents the differential of its integration path, and F. ds represents the product of quantities =fx*dx+fy*dy f=fxi+fyj(i j is the unit vector on the x y axis). Also used for Ampere's loop law: ∮L B*dl =μ0*∑I (L is subscript, B and dl are vectors). When used as a feather, it is used with "". Sogou typing, QQ typing and intelligent ABC can all be used to type this symbol. In the item of "Mathematical Symbol", you can enter it with the keypad.
Not less than this symbol is not less than (that is, greater than or equal to) symbol, also written as "≥". This symbol is often used for screen names.
This symbol is not greater than the symbol, and it is also written as "≤". This symbol is often used for screen names.
I hope it helps. All the above are from Baidu Encyclopedia.