Belongs to, and the mathematical symbol is "∈", indicating the relationship between elements and sets.

If a∈A, then A belongs to set A, and A is an element in set A ... If A? A, then A does not belong to set A, and A is not an element in set A. ..

Generally speaking, the totality of specified objects is called a set, which is represented by capital letters A, B, C, D ...; Each object in a set is called an element of this set, which is represented by lowercase letters A, B, C and D. ...

Belongs to, and the mathematical symbol is "∈", indicating the relationship between elements and sets. 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 set a, say that a does not belong to set a, and record it as a? Answer.

For example, a represents the set of "all prime numbers in 1~20", so there is 3 ∈ a.

Extended data

Does not belong to:?

For example, a ∈ r: a is a∈R:a number; Answer? N: a is not a natural number.

In solid geometry, the symbol "∈" is used to represent the positional relationship between points, lines and surfaces.

Example:

A∈l means that point a is on a straight line L.

A∈α means that point A is on plane α.